April 12, 2021
Feldspars
Figure 1 - Feldspar
Credit: Dave Dyet, 2007, Wikimedia Commons
Feldspar is a general name for a family of minerals that have historically been grouped together because they have similar characteristics in the field. They are commonly divided into two groups: plagioclase feldspars and alkali feldspars. About half the minerals in the Earth's crust are feldspar of one kind or another. Feldspars are found in most igneous and metamorphic rocks. Among sedimentary rocks, feldspars are rare except in arkose, a sandstone where many of the grains are feldspar. Figure 2, shows the relative abundance of the most common rock forming minerals.
General Properties
In color, feldspars are usually white, pink, gray or brown. However they can also be colorless, yellow, orange, red, black, blue, green. One variety, labradorite, has a distinctive blue colour, as shown in Figure 3. Feldspars are usually translucent to opaque and are only rarely transparent. If you mark a streak plate with feldspar, the streak will be white. The specific gravity of feldspars vary from 2.5 to 2.8. On Moh's Hardness Scale, the hardness of feldspars vary from 6.0 to 6.5. The lustre of feldspars is usually vitreous but can be pearly on some cleavage faces. Feldspars display perfect cleavage in two directions, usually intersecting at close to 90 degrees. This perfect 90 degree cleavage, together with consistent hardness, specific gravity and pearly luster on the cleavage faces, are the diagnostic characteristics of feldspar.
Figure 3 - Labradorite
Credit Linas Juozėnas, Wikimedia Commons
Chemically, all feldspars
are aluminum silicates with the general formula of
Figure 4 - Ternary Diagram of Feldspar Chemistry
As shown in Figure 4, the alkali feldspar series and the plagioclase feldspar series are two solid solution series that intersect at albite.
The plagioclase series ranges from pure sodium feldspar (albite - NaAlSi3O8) to pure calcium feldspar (anorthite - CaAl2Si2O8) Other minerals in the plagioclase series include oligioclase, andesine, labradorite, and bytownite. Plagioclase minerals are the most common feldspar.
The alkali feldspars, also called K feldspars or K-spar, are a solid solution series that ranges from pure sodium feldspar (albite - NaAlSi3O8) to pure potassium feldspar (orthoclase and microcline -KAlSi3O8). In between these endpoints are anorthoclase and sanidine.
In some cases, other cations substitute for the calcium, potassium and/or sodium to produce rare minerals; these include:
Buddingtonite ((NH4)(AlSi3)O8) an ammonium feldspar;
Banalsite (Na2BaAl4Si4O16) and Celsian (BaAl2Si2O8) barium feldspars; and
Stronalsite (Na2SrAl4Si4O16) a strontium feldspar.
The Uses of Feldspar
In 2020, 23,000,000 metric tonnes of feldspar were mined worldwide. The primary uses of feldspar are for glass and ceramics. For example, a growing segment of the market is the use of feldspar in the production of glass for solar panels. (USGS Mineral Commodity Summaries, Jan. 2021, pp 58-59)
Some feldspars are also used to make jewelry, these include Amazonite, Labradorite, Moonstone, and Sunstone.
Standard Caveat
The purpose of my weblog postings is to spark people's curiosity in geology. Don't entirely believe me until you've done your own research and checked the evidence. If I have sparked your curiosity in the subject of this posting, follow up with some of the links provided here. If you want to, go out into the field and examine some rocks on your own with the help of a good field guide. Follow the evidence and make up your own mind.
April 5, 2021
Rock-forming Minerals - Quartz
"Quartz
Crystals" by Mik Hartwell is licensed under CC BY-SA 2.0
The theme for the next few postings on this weblog will be rock-forming minerals. There are lots of them, so this theme could carry on for a few months. We'll look only at the most common minerals that people are likely to encounter, if you really want to dig into the subject, I suggest starting with these books:
Pough, F, 1998, A Field Guide to Rocks and Minerals (Peterson Field Guides), 5th Ed., Houghton Mifflin Harcourt, Boston, MA, USA
Deer, W., R. Howie, & J. Zussman, 1966, Introduction to the Rock Forming Minerals, Longman Group. Ltd., London, U.K.
Basic Properties of Quartz
Chemically, quartz is silicon oxide or silica. Pure quartz is clear to white, but with impurities and inclusions it can be any of a number of colours including gray, purple, yellow, brown, black, pink, green, and red. It is transparent to translucent and has a typically vitreous lustre. On Mohs' Hardness Scale quartz has a hardness of seven. When broken, quartz does not generally show cleavage but does show a characteristic conchoidal fracture. Quartz tends to form hexagonal crystals, as is Figure 1, above.
Varieties of Quartz
The main varieties of quartz that are found in nature are:
Standard Quartz: also called low quartz or α quartz, is the most common form of quartz. It is stable at normal temperatures and is found in most igneous and metamorphic rocks. Sand and sandstones are mostly made up of this kind of quartz. At high temperatures and pressures, it becomes high quartz, also called β quartz.
Chalcedony:is the microcrystalline or cryptocrystalline form of standard quartz. The term includes a variety of stones including flint, chert, jasper, and agate as well as chalcedony.
Tridymite: is a variety of quartz often found in acid igneous rocks such as obsidian, rhyolite, andesite, trachyte, dacite and tuff. It has slightly different optical qualities than standard quartz and often occurs as twinned crystals.
Cristobalite: like tridymite, cristobalite is also found in igneous volcanic rocks such as obsidian, rhyolite, andesite, trachyte, dacite and olivine basalt. Opal is a hydrous cryptocrystalline form of cristobalite.
Coesite and stishovite: are high pressure/high temperature varieties of quartz formed during events such as meteor impacts.
To get an idea of the conditions under which the various varieties of quartz form, Figure 2 is a phase diagram for silica:
The Uses of Quartz
Among the earliest uses for quartz was to make cutting tools. Knives, projectile points, and axes made from quartz varieties were among the earliest cutting tools that people made. The art of flint knapping is being rediscovered by archeologists, hobbyists and people who are researching ultra-sharp surgical tools. The conchoidal fractures of flint and other forms of chalcedony create some of the sharpest tools known to us, so if you take up flint knapping as a hobby, get some thick leather gloves. You might also want to have some Band-Aids © and Polysporin ©.
In more modern times, flint and steel were commonly used to start fires before chemical matches were in general use. A related use was to spark gunpowder in flintlock guns.
Another one of the original uses of quartz was as jewelry. Semiprecious stones that are varieties of quartz include:
Other artwork made from quartz includes items such as crystal skulls and crystal balls. A lot of this kind of artwork has been made to aid spiritual pursuits such as mediation and divination.
Quartz sand is used in applications such as abrasives, masonry (as the sand in mortar), glass, ceramics, enamel ware, and for foundry sand as well as for petroleum recovery by hydraulic fracturing.
Quartz crystals are used in electronics; some of you may have built a crystal radio at one time or another. Quartz is especially important as the source for the silicon that is used to make electronic devices like the one are using now. Our electronic village depends on silicon derived from quartz.
Standard Caveat
I am going to include this caveat in my postings from now on.
The purpose of my weblog postings is to spark people's curiosity in geology. Don't entirely believe me until you've done your own research and checked the evidence. If I have sparked your curiosity in the subject of this posting, follow up with some of the links provided here. If you want to, go out into the field and examine some rocks on your own with the help of a good field guide. Follow the evidence and make up your own mind.
March 29, 2021
Geohazards - Tsunamis
I am going to finish up my discussion of geohazards (for now) with a post on tsunamis. Tsunamis can kill lots people and smash up their property; this is not pleasant at all.
Features of Tsunamis
The word tsunami comes from Japanese. Living on the so called "Ring of Fire" seismic zone, the Japanese have a lot of experience with tsunamis. An older term in English was tidal wave, but this fell out of use since its confusion with tidal bores and storm tides.
To get a tsunami, something needs to displace a vast quantity of water. Volcanic explosions and the collapse of volcanic caldera under or next to the ocean can do this. Earthquakes alone can cause a tsunami but they can also trigger undersea landslides that in turn lead to a tsunami. If we really have a bad day, an extraterrestrial impactor, like an asteroid or comet, can fall into the ocean, also generating a tsunami.
The term tsunami literally translates as "harbour wave" from Japanese and this leads to an interesting feature about them. At sea, a tsunami will appear no bigger than any other swell and may not be noticeable in a rough sea. However, once the wave approaches land, for example when it enters a harbour, the wave piles up and can become metres high. Figure 2 illustrates this process.
Infamous Tsunamis
Tsunamis can be very destructive, here is a list of some most deadly tsunamis:
Indian Ocean, December 26, 2004
Triggered by a 9.1 magnitude earthquake under the Indian
Ocean, the official death toll for this tsunami was 227,898.
Messina, Italy, December 28, 1908
This tsunami was triggered by a magnitude 7.5 earthquake
that in turn set off an undersea landslide.
Estimates of the death toll range from 100,000 to 200,000 with 70,000 of
those in Messina.
Lisbon, Portugal, November 1, 1755
This tragedy began with an earthquake magnitude of 8.5 to
9.0 under the Atlantic Ocean offshore of Lisbon, Portugal. The earthquake caused building collapses, fires
and also triggered a tsunami with a 20 metre wave. This unfortunate combination of events killed
about 40,000 to 50,000 in Portugal, Spain, and Morocco.
Krakatoa, Indonesia, August 1883
The explosion of the Krakatoa volcano in August 1883
generated a tsunami 43 metres high.
About 40,000people were killed.
Fukushima, Japan, March 11, 2011
Also
called the Tōhoku Earthquake, this began with a 9.0 magnitude earthquake under
the Pacific Ocean offshore of Tōhoku on Honshu Island, Japan. The subsequent 40 metre high tsunami killed more
than 18,000 people and destroyed approximately $235 billion (USD) worth of
property including critical portions of the Fukushima Dai-ichi Nuclear
Generating Plant. The Dai-ichi Plant had a catastrophic
failure leading to the release of dangerous levels of radiation both onto the
surrounding land and into the Pacific Ocean.
An interesting feature of the Fukushima tsunami is that there are many stone markers in Japan showing the maximum inland intrusion of previous tsunamis. Some of these are uphill from the Fukushima Dai-ichi Nuclear Plant. In some ways, the Fukushima Dai-ichi Plant was an accident waiting to happen since earthquakes and tsunami are as inevitable in Japan as are blizzards in Canada. It was a lesson that did not need to be learned again.
Sauve qui peut
If you find yourself in an area where tsunami are possible, as in Figure 3, below, such as along the sea shore, keep the following in mind:
If you feel a earthquake, prepare to seek higher ground.
Listen on the radio for tsunami warnings, some places also send out warnings to smart phones and some places have no warning system at all
If you see the ocean suddenly recede, this means that the tsunami is imminent. Go to higher ground immediately. Don't stick around to get photos and videos. Getting that selfie might kill you.
References
Wikimedia Commons, Mar.2015, File:Tsunami by hokusai 19th century.jpg, https://commons.wikimedia.org/wiki/File:Tsunami_by_hokusai_19th_century.jpg
WPClipart, accessed March 2021, tsunami approaching landhttps://wpclipart.com/weather/tsunami/tsunami_approaching_land.png.html
Johnson, B., Aug. 2020, World's Worst Tsunamis, ThoughtCo, thoughtco.com/worlds-worst-tsunamis-3555041.
Disaster Rally, accessed March 2021,What to Do in Case of Tsunami Before, During, and After, https://disasterrally.com/what-to-do-in-case-of-tsunami/
March 22, 2021
Geohazards - Landslides
Figure 1 - Last Chance Grade Landslide
Stevie Nicks wrote her song, Landslide, in response
to the many professional troubles that she and her band, Fleetwood Mac, were
having at the time. Everything seemed to be crashing down at once, just like a landslide
Landslide Causes
The basic cause of landslides is the action of gravity on a vulnerable geological feature combined with something that triggers the failure. More specifically, landslides may be caused by one or more of the following factors:
1. Geological causes
Weak or sensitive materials
Weathered materials
Sheared, jointed, or fissured materials
Adversely oriented discontinuity (bedding, schistosity, fault, unconformity, contact, and so forth)
Contrast in permeability and/or stiffness of materials
2. Morphological causes
Tectonic or volcanic uplift
Glacial rebound
Fluvial, wave, or glacial erosion of slope toe or lateral margins
Subterranean erosion (solution, piping)
Deposition loading slope or its crest
Vegetation removal (by fire, drought)
Thawing
Freeze-and-thaw weathering
Shrink-and-swell weathering
3. Human causes
Excavation of slope or its toe
Loading of slope or its crest
Draw down of reservoirs
Deforestation
Irrigation
Mining
Artificial vibration
Water leakage from utilities
(From USGS, 2004
Features of a Landslide
Before discussing the types of landslides, it is helpful to identify the features of a landslide, as shown in Figure 2, below.
Figure 2 -Features of a Landslide
Types of Landslides
Figure 3, below, illustrates the main types of landslides.
Figure 3 - Types of Landslides
In a rotational landslide (Fig. 3A), the
surface of rupture is curved concavely upward and movement of the slide is
roughly rotational about an axis that is parallel to the ground surface and
transverse across the slide
Translational landslides (Fig. 3B) are where the landslide mass
moves along a roughly planar surface with little rotation or backward tilting
A block slide (Fig 3C) is a kind of translational
slide where the moving mass consists of a single unit or a few closely related
units that move downslope as a relatively coherent mass
A rock fall (Fig. 3D is just as the name suggests; masses
of geologic materials, such as rocks and boulders become detached from steep
slopes or cliffs
In a topple, (Fig. 3E) the failure of the material unit is by the
forward rotation of a unit or units about some pivotal point, below or low in
the unit
Debris flows (Fig. 3F) are a form of rapid mass movement in
which a combination of loose soil, rock, organic matter, air, and water
mobilize as a slurry that flows downslope
A debris avalanche (Fig.3G) is an
extremely fast variety of a debris flow
Earthflows (Fig. 3H) have a characteristic “hourglass” shape;
the slope material liquefies, runs out, and forms a bowl or depression at the
head of the earthflow
In this context, creep (Fig. 3I) isn't the obnoxious
fellow leering at passersby but, rather, is the slow, sometimes almost
imperceptible, steady, downward movement of soil and/or rock
Lateral spreads (Figure 3J) occur on very gentle slopes or flat
terrain and are marked by lateral movement of the soil, often due to
liquefaction of saturated soils with little cohesion. Lateral spreads are often
triggered by earthquakes but can also be artificially induced
Worldwide Risks of Landslides
Landslides are most common in areas of high relief, such as in mountainous terrain. Risks to human life increase where there are greater densities of population; both from the number of people in proximity to the potential unstable ground and from the likelihood of human activity that increases the instability. Areas of high rainfall are also prone to landslides where those areas coincide with the terrain and human factors.
Figure 4, prepared by the NASA Earth Observatory, shows the worldwide risks of landslides to human life and property.
Figure 4 - Global View of Landslide Susceptibility
Afterword
As a geohazard, landslides are a serious threat to human life and property. Understanding the causes and mechanics of landslides is a necessary precaution in areas prone to them. Just as important is understanding how human activities can increase or mitigate the threat from landslides.
Back to where we started at the beginning of the post. We saw Stevie Nicks writing Landslide when her professional life seemed to be falling down. So, what happened next? Well, Landslide went on to be a big hit. Since then Stevie Nicks has had a successful career, both with Fleetwood Mac and also as a solo artist. Other singers have covered the song and Stevie Nicks continues to sing it to this day. While having little to say on the science of landslides, art like the song Landslide can teach us lessons about coping with the inevitable grief and loss that will occur in our lives.
Where there's life, there's hope.
References
Wikimedia Commons, Feb. 2021, File:2020-0301 LastChanceGradeLandslide.jpg, https://commons.wikimedia.org/wiki/File:2020-0301_LastChanceGradeLandslide.jpg
Wikipedia, Mar. 2021, Landslide (Fleetwood Mac song), https://en.wikipedia.org/wiki/Landslide_(Fleetwood_Mac_song)
United States Geological Survey (USGS), Jul. 2004, Landslide Types and Processes, https://pubs.usgs.gov/fs/2004/3072/fs-2004-3072.html
NASA Earth Observatory, March, 2017, A Global View of Landslide Susceptibility, https://earthobservatory.nasa.gov/images/89937/a-global-view-of-landslide-susceptibility?src=ve
March 15, 2021
Earthquakes in Divers Places
Figure 1 - Croatian Earthquake, December 2020
For nation shall rise
against nation, and kingdom against kingdom: and there shall be earthquakes in
divers places, and there shall be famines and troubles: these are the
beginnings of sorrows.
When Jesus of Nazareth warned his followers of what to expect in the future, he included earthquakes among the many troubles that were coming their way. This isn't surprising, since in Jesus' day, and indeed for most of human history, earthquakes and other natural disasters were seen as divine punishment or warning that something important was coming our way. However, with the development of the modern science of geology, we have a better understanding of earthquakes as natural processes.
Faults
So, what is an earthquake? An earthquake is a movement of a portion of the earth's crust, usually along a pre-existing break in the crust that we call a fault. The animations below show the three main kinds of faults.
Strike-slip faults,also
called transform faults are vertical (or nearly vertical) fractures
where the blocks have mostly moved horizontally. If the block opposite an
observer looking across the fault moves to the right, the slip style is termed
right-lateral; if the block moves to the left, the motion is termed
left-lateral. Animation link
Normal, or Dip-slip, faults are
inclined fractures where the blocks have mostly shifted vertically. If the rock
mass above an inclined fault moves down, the fault is termed normal, whereas if
the rock above the fault moves up, the fault is termed a Reverse fault.Animation link
A thrust fault is a reverse fault with a dip of 45° or less, a very
low angle. The animation shows a reverse fault which is a steeper-angle fault,
but it moves the same way. Animation link
Causes of Earthquakes
So what can cause the earth's crust to move? There are four main causes:
Movement of tectonic plates
Volcanism
Isostatic rebound
Anthropogenic causes
Tectonic Plate Movement
The earth's crust is divided into a number of distinct plates. Plate tectonics is worth at least one blog post, maybe more, and I shall discuss it in future postings. For now, it is enough to note that the plates move. Earthquakes caused by tectonic activity occur where tectonic plates move next each other.
Figure 2 shows the major tectonic plates in the world and the direction of movement.
Figure 2 - Tectonic Plates
Volcanism
The movement of magma and lava before and during volcanic eruptions can cause many
earthquakes. As I discussed last week, current earthquakes
at the Reykjanes Peninsula in SW Iceland portend volcanic eruptions there
Isostatic Rebound
When the continental glaciers began melting around 15,000 years ago, a great weight was taken off the earth. Once that weight was removed, the earth's crust rebounded. It isn't a gradual process but occurs as intermittent movements. These movements cause earthquakes, generally minor. Many of the earthquakes in Canada, especially those occurring east of the Rockies, are due to glacial rebound.
There is a good summary of
isostatic rebound on the Wikipedia page Post-glacial rebound
Anthropogenic Causes
Human activities can cause earthquakes, these activities include
Mining: collapsing mine tunnels in underground coal mining
Mining and construction: excavation with explosives
Oil and natural gas extraction: formation fracturing (fracking)
Waste Disposal: injecting waste fluids underground
Dams: the weight of water behind a dam
Weapons: nuclear weapons testing
One concern is that human activity can trigger existing
faults and inadvertently cause large earthquakes
Infamous Earthquakes
When earthquakes occur in densely populated areas, huge
numbers of people can be killed, either by collapsing buildings or by knock on
effects such as tsunami. Here is a list
of the 10 deadliest earthquakes in history
1. Shaanxi, China (1556)
With an estimated strength of 8.0 on the Richter Scale, this earthquake killed approximately 830,000 people on the morning of 23rd January, 1556. Many people the Shaanxi region lived in caves dug in the loess soil and the earthquake collapsed many of these caves. Also, the earthquake triggered landslides, killing more people.
2. Haiyuan, China (1920)
In the evening of December 16th, 1920, an earthquake measuring 7.5 to 8.5 on the Richter Scale struck Gansu Province in China. Estimates of the total death toll attributed to the earthquake range between 240,000 and 275,00 and include people who perished from exposure in the harsh winter weather following the earthquake.
3. Tangshan, China (1976)
Often called The Great Tangshan Earthquake, this earthquake struck the city of Tangshan, China on July 28th, 1976 at 4:00 AM. Measuring 7.8 on the Richter Scale, the initial earthquake was followed by an aftershock 16 hours later. Of the approximately 1 million inhabitants of Tangshan, approximately 255,000 people were killed, mostly by collapsing buildings.
4. Antioch, Eastern Roman Empire (526)
Located at modern day Antakya in Turkey, ancient Antioch was a major city in the Eastern Roman Empire. The initial 7.0 magnitude earthquake in 526 was followed by aftershocks that lasted for 18 months. Approximately 250,000 people were killed, mostly by falling buildings.
5. Indian Ocean (2004)
On Boxing Day 2004, a 9.3 magnitude earthquake lasting almost 10 minutes occurred under the Indian Ocean triggering a massive tsunami. Approximately 230,000 people were killed in Indonesia, Sri Lanka, India and Thailand.
6. Aleppo, Syria (1138)
Located at the north end of the Dead Sea rift system, Aleppo, Syria is prone to periodic earthquakes. Several earthquakes hit the region from October 1138 to May 1159 leading to the deaths of approximately 230,000, mostly from collapsing buildings.
7. Haiti (2010)
The main 7.0 magnitude earthquake occurred January 12, 2010 and was followed by 52 aftershocks, some with a magnitude of 4.5 . The estimated death toll was more than 160,000.
8. Damghan, Persia (856)
Occurring at Damghan in modern day Iran, the 856 earthquake had an estimated magnitude of 7.9. The earthquake affected an area with a 350 km radius around the epicentre. Approximately 200,000 people were killed in the towns of Ahevanu, Asta, Tash, Bastam and Shahrud as well as in surrounding villages.
9. Dvin, Armenia (893)
Dvin, the capital of ancient Armenia, (now ruins near Verin Dvin, Armenia) was hit by an earthquake on December 26, 893. Approximately 150,000 people were killed.
10. Messina, Italy (1908)
Hitting the city of Messina with an estimated magnitude of 7.1, the December 28, 1908 earthquake destroyed up to 90% of the buildings in the city and generated a 12 m high tsunami. About 123,000 people died as the result of the building collapses and tsunami.
As always, feel free to follow up on the references listed below to learn more about earthquakes.
References
USA Today, Dec. 29, 2020, Rescuers comb through rubble after Croatia earthquake, https://www.usatoday.com/videos/news/world/2020/12/29/rescuers-comb-through-rubble-after-croatia-earthquake/4079848001/
Gospel of Mark, Ch. 13, v. 8, King James Version, https://biblehub.com/kjv/mark/13.htm
United States Geological Survey (USGS), 2014, Strike-Slip Fault, https://www.usgs.gov/media/videos/strike-slip-fault
USGS, 2014, Normal Fault, https://www.usgs.gov/media/videos/normal-fault
USGS, 2014, Thrust Fault, https://www.usgs.gov/media/videos/thrust-fault
Weebly, Accessed March 2021, Plate Tectonics, Plate Boundaries & Tectonics, https://plateboundaries111.weebly.com/plate-tectonics.html
McGarvie, D., Mar. 4, 2021, South-west Iceland is shaking – and may be about to erupt, The Conversation, Academic Journalism Society, https://theconversation.com/south-west-iceland-is-shaking-and-may-be-about-to-erupt-156510
Wikipedia, January 2021, Post-glacial rebound, https://en.wikipedia.org/wiki/Post-glacial_rebound
Mulargia, F., Bizzarri, A., 2014, Anthropogenic Triggering of Large Earthquakes. Sci Rep 4, 6100. https://doi.org/10.1038/srep06100
TOP10HQ, Top 10 Deadliest Earthquakes in History, https://www.top10hq.com/top-10-deadliest-earthquakes-history/, accessed March 2021
March 8, 2021
More on Volcanoes as a Geohazard
Figure 1 - Mt. Sinabung, March 2, 2021 1
After last week's posting, two more volcanoes were in the news: Mt. Sinabung in Indonesia erupted 1 and geologists warned that Keilir Volcano in Iceland will soon erupt 2. With that in mind, I thought that it would be worthwhile to look further into the dangers from volcanoes.
The Nature of Lava
Erupting volcanoes spew out hot gases, molten rock, rock fragments and dust, so there are some pretty obvious dangers. Just how dangerous depends on the nature of the lava produced by the eruption. Lava varies in viscosity from fairly fluid to very viscous. Fluid lava will simply flow out of the volcano's pipe while viscous lava may explode. The presence or absence of water will also affect the eruption.
The viscosity of lava depends in large part its chemical composition, especially its silica content. The best way to describe this composition is by way of the minerals that will crystallize out of the melt. Figure 2 shows a general classification of igneous rocks, volcanic rocks are considered extrusive igneous rocks.
Figure 2 - General Classification Igneous Rocks
In general, the most fluid lavas will be those that form mafic and ultramafic rocks. The term "mafic" refers to the dark colour of rock dominated by minerals such as olivine, pyroxene and calcium rich plagioclase feldspar. At the other end of the spectrum, lavas that produce felsic rock will tend to very viscous; the term "felsic" refers to the lighter colour of the rock dominated by minerals such as orthoclase (potassium feldspar), quartz, and sodium rich plagioclase.
Hazards from Volcanic Eruptions
Lava flows
Figure 3 - Eruption of Kilauea
Molten rock flowing directly from a volcanic pipe or vent is probably the safest kind of volcanic eruption to be around. An example of a lava flow are the ongoing eruptions at Kilauea, Hawaii.
Although relatively fluid, molten lava moves slowly and is
easily avoided. However, there are
distinct dangers from flowing lava. Hot flowing lava will cause any flammable
item in the vicinity to catch on fire including
vegetation and wooden structures.
Also, flowing lava can bury anything that gets in the way its way
including cars, roads and buildings.
Pyroclastic Flows
Figure 4 - Pyroclastic Flow,Mt.
Merapi, Indonesia.
Moving downhill at 80 km/hr; you really want avoid these
hellishly hot (200 - 700 degrees C ) avalanches of volcanic dust, gases and steam.
Be prepared to run far, pyroclastic flows can travel five to fifteen km from
the volcanic eruption. Pyroclastic flows
are associated with explosive eruptions such as at Mt. Pinatubo, Philippines,
El Chicon, Mexico and Mt. Merapi, Indonesia (Fig. 4, above).
Debris Flows and Lahar
Figure 5 - Lahar at
Mt. St. Helens
Another hazard from volcanic are debris flows, sometimes called
lahars. Mixtures of volcanic ash, soil, rocks, water, and any other debris the
lahar pick up along the way (trees, dead bodies), lahars travel down the steep
slopes of volcanoes, during or after volcanic eruptions. The water often comes
from melted ice. The debris flow has the
consistency of cement, and will often travel long distances along river valleys
downstream from the volcano. Lahars from
Mt. St. Helens, in Washington State, traveled
up to 97 km from the volcano.
Landslides
Volcanic landslides occur
when the
structure of the main body of a volcano fails before, during or after an eruption
I'll discuss more about landslides in an upcoming posting.
Volcanic Ash and Tephra
Explosively
erupting volcanoes discharge various sizes of material ranging from very fine
silt to cobbles and boulders The fine grained material is usually called
"volcanic ash" and the larger material is often called
"tephra"
The obvious hazard from volcanic ash and tephra is burial. So, unless you want to become a future exhibit in a museum, like the unfortunate inhabitant of Pompeii below, you would be wise to vacate areas suffering volcanic ash falls.
Figure 6 - Cast of
Pompeii Resident
You may have to travel far, though; volcanic ash can travel
hundreds of miles from the volcanic eruption
Another danger from volcanic ash is inhalation. Volcanic ash
is made up of fine particles of volcanic glass
Eyjafjallajokull is on the Reykjanes Peninsula in SW
Iceland. Also on the Reykjanes Peninsula is the Keilir Volcano, which as we noted at the
beginning of this post, may be ready to erupt
Volcanic Gases
Volcanic eruptions usually include emissions of various
gases such as steam, carbon dioxide, sulphur dioxide and hydrogen
sulphide. Sometimes the gaseous
emissions alone are sufficient to cause great harm. Sulphur dioxide and hydrogen sulphide are
both poisonous gases and high concentrations of carbon dioxide present an
asphyxiation hazard.
The release of carbon dioxide from Lake Nyos, a lake in a
volcanic crater in Cameroon, killed approximately 1700 people August 26, 1986
Pay Your Money and Take Your Chances
Volcanoes are both dangerous and beautiful. If you live in the vicinity of an active volcano, familiarize yourself with its eruption history and characteristics. If you plan to visit an active volcano, enjoy the spectacle but keep the risks in mind. Try not to be like these tourists at Eyjafjallajokull.
Notes on Grain Size
When referring to the grain size of material, I use the Wentworth
Scale
Table 1 - Wentworth Grain Size Scale
References
Howes, N, March 2, 2021, Indonesian volcano erupts again, here's why it has frequent blasts, Yahoo News, https://news.yahoo.com/indonesian-volcano-erupts-again-heres-014300551.html?guccounter=1&guce_referrer=aHR0cHM6Ly9kdWNrZHVja2dvLmNvbS8&guce_referrer_sig=AQAAAFGdwz75_gFUlVLxURwBVLYf0GyndgPsVIe49WPEnKdqgYjy17FyPOqIfDWfzSdrbarYHjblsT7EWI6HJfpt0goEgFZ316LWnYUgLbGCxJKGgAFKigY6YFhXTFJ2A9trMDVc8XfT3M7U2w06-SM7SkfwvgJfO4CLeWSw0EBiuoeT
Henley, J., March 3, 2021, Scientists in Iceland say ‘strong signs’ volcanic eruption is imminent, The Guardian, https://www.theguardian.com/world/2021/mar/03/scientists-in-iceland-say-strong-signs-volcanic-eruption-is-imminent
Wikimedia Commons, Oct.2020, File:Igneous rocks.jpg, https://commons.wikimedia.org/wiki/File:Igneous_rocks.jpg
Wikimedia Commons, Sept.2020, File:Eruption of the Kilauea volcano.jpg, https://commons.wikimedia.org/wiki/File:Eruption_of_the_Kilauea_volcano.jpg
American Geosciences Institute, 2021, What kinds of hazards are associated with volcanic eruptions?, https://www.americangeosciences.org/critical-issues/faq/what-kinds-hazards-are-associated-volcanic-eruptions
Mongin, M., Jan. 2009, Pyroclastic Flow, Penn State, "pyroclastic flow" by pennstatenews is licensed under CC BY-NC 2.0, https://www.flickr.com/photos/53130103@N05/4950560761
Wikimedia Commons, Oct.2020, File:Lahar, Mount St. Helens.jpg, https://commons.wikimedia.org/wiki/File:Lahar,_Mount_St._Helens.jpg
Wikimedia Commons, Sept.2020, File:Pompeii casts 06.jpg, https://commons.wikimedia.org/wiki/File:Pompeii_casts_06.jpg
USGS Volcanic Ash Falls Impacts Group, Feb. 2016, Volcanic Ash Impacts and Mitigation, Aviation, https://volcanoes.usgs.gov/volcanic_ash/ash_clouds_air_routes_eyjafjallajokull.html
McGarvie, D., Mar. 4, 2021, South-west Iceland is shaking – and may be about to erupt, The Conversation, Academic Journalism Society, https://theconversation.com/south-west-iceland-is-shaking-and-may-be-about-to-erupt-156510
Oregon State University, 2021, Volcano World, Lake Nyos - Silent but Deadly, http://volcano.oregonstate.edu/silent-deadly
Wentworth, C.K., 1922, A Scale of Grade and Class Terms for Clastic Sediments, The Journal of Geology, Vol. 30, No. 5 (Jul. - Aug., 1922), pp. 377-392, The University of Chicago Press, https://www.jstor.org/stable/30063207?seq=1#metadata_info_tab_contents
Wikimedia Commons, September 2020, File:Wentworth scale.png, https://commons.wikimedia.org/wiki/File:Wentworth_scale.png
March 1, 2021
Geohazards - Volcanoes
Figure 1 - Mount Etna Volcano Feb. 24,
2021.
(Credit: AP Photo/Salvatore Allegra)
I noticed in the news this past week that Mount Etna in Italy is erupting again
What's a Geohazard?
Geology is about the real world, and the world can be a dangerous place. Geohazards are any dangerous geological condition. These include: volcanoes, earthquakes, landslides, tsunami and floods. There are many ways that the Earth can kill us and we had better be aware of those threats for our own self protection.
For general information on
geohazards, you might want to read the Natural Resources Canada
document, Evaluation of the Geohazards
and Public Safety Program Sub-activity
Where are Volcanoes Found?
Volcanoes on the Earth are intimately connected to the movement of the crustal plates in the process called Plate Tectonics. (I'll have to discuss Plate Tectonics in a future blog posting.) Generally, volcanoes are found at plate boundaries. Volcanoes can also be found at so called "hot spots" in the middle of a plate.
Figure 2 shows the general location of the tectonic plates and the locations of volcanoes.
Figure 2 - Volcanoes and Plate Boundaries
Active volcanic regions in Canada are found in five areas in the Western Cordillera. Figure 3 shows the locations of active volcanoes in Canada.
Figure 3 - Active Volcanoes in Canada
Anatomy of a Volcano
The main features of a volcano are, from the bottom up:
The magma chamber, this is where the molten magma accumulates;
The pipe through which the magma flows to emerge through the vent in the chamber as either lava, volcanic ash and/or volcanic bombs;
The cone that is made up of accumulated layers of lava, volcanic ash and/or volcanic bombs.
Figure 4 - Anatomy of a Volcano
Types of Volcanoes
Generally, there are four kinds of volcanoes, the kind of lava produced by a volcano will largely determine the form that a volcano takes:
1. Cinder cone volcanoes
These are made up of
a collection of volcanic dust, pebbles, cobbles and boulders (volcanic
bombs). Volcanoes that erupt viscous lavas
will form cinder cones. Paricutin, in Mexico, is a typical cinder cone volcano.
Figure
5 - Paricutin Volcano
2. Shield volcanoes
These are made up of
consecutive lava flows formed from relatively fluid lava as in Figure 6, below. The islands of Hawaii and Iceland are giant
shield volcanoes.
Figure 6 - Internal Structure of a Shield Volcano
3. Composite volcanoes
These are made up of different layers of lava flows and volcanic
ash. These are formed where the
underlying magma chamber produces alternating fluid lava and viscous lava as
in Figure 7, below.
Figure 7 - Internal Structure of a Composite Volcano
4. Lava domes
These form from relatively
small, bulbous masses of lava, too viscous to flow any great distance. As a result, when extruded through the pipe,
the lava piles over and around the volcano's vent. The Novarupta Dome, formed during the 1912 eruption of Katmai
Volcano in Alaska, is an example of a lava dome.
Figure 8-Novarupta Dome, Mt. Katmai, Alaska
Some Examples of Famous Volcanic Eruptions
Volcanoes can be deadly. Here are a four examples from history:
Thera, Greece, 1628 B.C
The volcano on the island of Thera (also called Santorini)
blew up with a huge explosion around 1628 B.C.
Approximately 40,000 people were killed by the explosion and the
subsequent 40 foot tsunamis. The blast
was heard 3,000 miles away
The destruction of the island severely weakened the Minoan
Civilization and, according to authors such as Dr. Charles Pellegrino, may be
the source of Plato’s myth about Atlantis
Mt. Vesuvius, 79 AD
The eruption of Mt. Vesuvius in 79 AD was famously recorded
by Gaius Plinius Caecilius Secundus(Pliny the Younger) in his correspondence with the historian Publius
Cornelius Tacitus (Tacitus). In Letters
LXV and LXVI, Pliny the Younger describes the eruption of Vesuvius and the death of his
uncle, Gaius Plinius Secundus (Pliny the Elder)
In those days, the Romans believed that leading citizens
should risk their lives for the common good. Pliny the Elder, a Roman Senator,
died trying to rescue people from the eruption. He was among the approximately
1,500 people that perished as a result of the eruption of Mt. Vesuvius
The eruption of Mt. Vesuvius in 79 AD buried the cities of Pompeii and Herculaneum and archaeological studies of the two buried cities have given us a unique glimpse into life during Roman times.
Tambora 1815
Tambora is found in Indonesia and on April 10, 1815 it
erupted with what has been described as the greatest explosion in recorded
history. The eruption spewed an
estimated 36 cubic miles of volcanic ash into the atmosphere. Approximately 88,000 people were killed in
the explosion.
The following year
was called the “Year Without Summer” and was marked by crop failures, famine
and general gloominess. Mary Shelley wrote her famous novel Frankenstein, that summer.
Krakatoa, August 1883
Krakatoa lies in the Sunda Straight between Java and
Sumatra. In May 1883, it began to erupt.
On August 27, 1883, it exploded with an equivalent force of 200 megatons
of TNT. The explosion and subsequent
tsunami killed approximately 36,000 people.
Mitigating the Hazard
Volcanoes are notoriously dangerous. If a volcano goes off in your neighbourhood, the
best course of action is to
Volcanologists, geologists who study volcanoes, are brave people as in Figure 9, below. I think that it would be fun to do this, don't you?
Figure 9 - USGS Geologist Sampling at Mauna Loa Volcano, Hawaii
Besides physical distancing when an eruption occurs, the best long term mitigation strategy for the danger from volcanoes is to study them. As a society, supporting the work of volcanologists is a good investment. We still have a lot to learn about volcanoes, especially about predicting the timing and scale of eruptions. Failure to prepare ourselves for the dangers in this world could be fatal for millions of people.
If you have a taste for disaster movies involving volcanoes, this is a good film.
As always, this is a big subject, and if volcanoes interest you, follow up on the references listed below.
References
Associated Press, Feb. 25, 2021, Mount Etna's recent eruption is a spectacular volcanic show, https://www.foxnews.com/world/mount-etna-puts-on-its-latest-spectacular-show
Volcano Discovery, Feb. 2021, Etna volcano updates and eruption news, https://www.volcanodiscovery.com/etna/news.html
Natural Resources Canada, 2013, Evaluation of the Geohazards and Public Safety Program Sub-activity (PAA Sub-activity 3.1.5), https://www.nrcan.gc.ca/nrcan/plans-performance-reports/strategic-evaluation-division/reports-plans-year/evaluation-reports-2014/evaluation-geohazards-and-public-safety-program-sub-activity-paa-sub-activity-315/16274
The Canadian Geotechnical Society, 2019, Geohazards, CGS Geohazards Conference Proceedings, https://www.cgs.ca/geohazards_committee.php
GeoHazards (ISSN 2624-795X), https://www.mdpi.com/journal/geohazards
Wikimedia Commons, Feb. 2017, File:Map plate tectonics world.gifhttps://commons.wikimedia.org/wiki/File:Map_plate_tectonics_world.gif
Gravesande, D, July 2018, Volcanoes in Canada: Are they ready to rumble?, Natural Resources Canada, https://www.nrcan.gc.ca/simply-science/21282
Watson, J., 2011, Principal Types of Volcanoes, United States Geological Survey, https://pubs.usgs.gov/gip/volc/types.html
Wikimedia Commons, November 2020, File:Paricutín volcano.jpg, https://commons.wikimedia.org/wiki/File:Paricut%C3%ADn_volcano.jpg
Wikimedia Commons, April 2019, File:Alaska Katmai Novarupta-Dom.jpg, https://commons.wikimedia.org/wiki/File:Alaska_Katmai_Novarupta-Dom.jpg
Whipps, H., 2008, How The Eruption of Thera Changed the World, https://www.livescience.com/4846-eruption-thera-changed-world.html
Pellegrino, C. R., 1991, Unearthing Atlantis, Random House Inc., New York, N.Y., U.S.A.
Bosanquet, F. C. T. (ed.), 2001, Letters LXV and LXVI in Letters of Pliny By Gaius Plinius Caecilius Secundus, translated by Translated by William Melmoth, https://www.gutenberg.org/files/2811/2811-h/2811-h.htm#link2H_4_0065
Wikipedia, February 2021, Eruption of Mount Vesuvius in 79, https://en.wikipedia.org/wiki/Eruption_of_Mount_Vesuvius_in_79
Live Science, 2012, The Greatest Eruption in Human History: Mount Tambora, https://www.livescience.com/31337-mount-tambora-image.html
National Center for Atmospheric Research, UCAR, 2012, Mount Tambora and the Year Without a Summer, https://scied.ucar.edu/shortcontent/mount-tambora-and-year-without-summer
Mary Bagley, M., 2017, Krakatoa Volcano: Facts About 1883 Eruption, https://www.livescience.com/28186-krakatoa.html
Wikimedia Commons, June 2009, File:Sampling lava with hammer and bucket.jpg, https://commons.wikimedia.org/wiki/File:Sampling_lava_with_hammer_and_bucket.jpg
February 22, 2021
Hydrogen, Helium, Lithium
Introduction
In last week's post on where the elements originated I noted that Hydrogen, Helium and Lithium were the only three elements created in the Big Bang. So, what is the geology of these three elements?
Hydrogen
Although it is the most common element in the Universe, free hydrogen is not common on the Earth. this is because free hydrogen is very reactive and the use of hydrogen can come to explosive ends as in Figure 1.
Figure 1 - Hydrogen is Very Reactive
https://commons.wikimedia.org/wiki/File:Hindenburg_disaster.jpg
Most of the hydrogen on earth is found in water, which is made up of hydrogen and oxygen. Hydrogen is also found in hydrocarbons: petroleum, natural gas and coal.
I won't spend too much time on hydrogen geology in this week's post since it can include a lot of topics, each of which is worth a post, or series of post, of its own:
Water
Erosion and sedimentary deposition;
Ocean and coastal geology,;
Caves and karst topography;
Glacial geology and periglacial landforms;
Hydrogeology and groundwater;
Minerals containing water such as hydrates.
Hydrocarbons
Exploration and extraction of petroleum, natural gas and coal deposits;
The origin of petroleum, natural gas and coal;
The economics of hydrocarbons including depletion.
The Hydrogen Economy
Hydrogen as an alternative energy source
I'll explore these themes in future posts.
Helium
Although helium is the second most abundant element in the Universe, it is rare on Earth. As a noble gas , it does not combine with other elements and, as a light gas, little would have remained in the atmosphere after the initial formation of the Earth. Most helium found in the Earth today is found as a component of natural gas, having been formed as a result of the radioactive decay of Uranium 238, as in Figure 2.
Figure 2 - Helium from Radioactive Decay of
U 238From : Weebly.com,
Radioactive Decay,
https://radioactivedecay9.weebly.com/what-is-radioactive-decay.html
According the U.S. Geological Survey, helium is used for the following applications:
magnetic resonance imaging, 30%;
lifting gas, 17%;
analytical and laboratory applications, 14%;
welding, 9%;
engineering and scientific applications, 6%;
leak detection and semiconductor manufacturing, 5% each;
and various other minor applications, 14%.
1
The United States has the largest reserves of Helium,
estimated at 3,100 million cubic metres (MCM), followed by Algeria (1,800 MCM) and Poland (25 MCM)
In Canada, most helium is produced in Saskatchewan and
Alberta as a by-product of natural gas production. Construction of a new helium purification
facility was announced in May 2020
Lithium
The last of our three Big Bang elements is lithium. Most people are familiar with lithium as a component in lithium ion and lithium polymer batteries. The main uses of lithium are:
batteries, 65%;
ceramics and glass, 18%;
lubricating greases, 5%;
polymer production, 3%;
continuous casting mold flux powders, 3%;
air treatment, 1%; and
other uses, 5%.
4
Lithium is also a highly reactive metal and its use in
lithium ion or lithium polymer batteries is known to cause fire in certain
circumstances. Here is an
example of what can happen
About ten minerals are known to contain lithium; in igneous rocks the most common lithium minerals are spodumene, petalite and lepidolite 6. In sedimentary rocks, lithium is found in the clay mineral, hectorite. Lithium can also be extracted from brines 6. The environments that lithium minerals and dissolved lithium are found include:
Lithium-Cesium-Tantalum Pegmatite Deposits;
Lithium-Enriched Granites;
Lithium Brine Deposits in Closed Basins;
Lithium in Other Brines;
Lithium-Clay Deposits;
Lithium-Zeolite Deposits.
6
Figure 3 shows the location of Lithium-Cesium-Tantalum Pegmatite Deposits worldwide.
Figure 3 Worldwide Lithium-Cesium-Tantalum Pegmatite Deposits
Figure 4 shows the location of lithium enriched brine and clay deposits worldwide
Figure 4 Worldwide Lithium
Enriched Brine and Clay Deposits
If
electric vehicles (EV) become more popular, we can expect a greater demand for
lithium to make the batteries for the EV.
One estimate of future demand was published in Mining.com Jan. 27, 2021 indicating
that if Tesla goes forward with their plan to build 20 million cars per year, it
will require 127,302 tons of lithium per year
Many
people believe that EV are more environmentally friendly than internal
combustion engine (ICE) vehicles. After
all, EV make no emissions. However, the
environmental cost of any vehicle system has to include not only the emissions
of the individual vehicles, but also the environmental effects of building the
vehicles. In the case of the lithium
required for batteries, we should consider the environmental effects of lithium
mining or brine extraction that can lead to surface and groundwater pollution
as well as landscape destruction
As always, environmental costs are a matter of trade offs. Switching to EV will reduce air pollution, especially in large cities where there are many motor vehicles. However, the trade off will be moving the environmental impacts from prosperous urban environments to the places where the necessary minerals are extracted. Many of these places are poor and have little in the way of environmental regulation, thus shifting the burden of the environmental costs from wealthy consumers to the impoverished people who live in the vicinity of the mineral production. That's our choice, that's the trade off for EV.
References
Peterson, J. P., January 2020, U.S. Geological Survey, Mineral Commodity Summaries, Helium,https://pubs.usgs.gov/periodicals/mcs2020/mcs2020.pdf, pp.76-77 Government of Sask., May 28, 2020, Canada’s Largest Helium Purification Facility To Be Built In Saskatchewan, https://www.saskatchewan.ca/government/news-and-media/2020/may/28/helium-facility
Daily Oil Bulletin, Jan. 21, 2021, North American Helium Launching Canada’s Largest Purification Facility in Saskatchewan, https://www.dailyoilbulletin.com/article/2021/1/12/north-american-helium-launching-canadas-largest-pu/
Jaskula, B. W., January 2020, U.S. Geological Survey, Mineral Commodity Summaries, Lithium,https://pubs.usgs.gov/periodicals/mcs2020/mcs2020.pdf, pp 98-99
Hakemon Mike, Apr. 12, 2017, Piercing Lithium Battery (Catches Fire!), https://www.youtube.com/watch?v=xbeQWkYPmfw
Bradley, D.C., Stillings, L.L., Jaskula, B.W., Munk, LeeAnn, and McCauley, A.D., 2017, Lithium, chap. K of Schulz, K.J., DeYoung, J.H., Jr., Seal, R.R., II, and Bradley, D.C., eds., Critical mineral resources of the United States—Economic and environmental geology and prospects for future supply: U.S. Geological Survey Professional Paper 1802, p. K1– K21, https://doi.org/10.3133/pp1802K
Els, F., Jan. 27, 2021, All the mines Tesla needs to build 20 million cars a year, Mining .com, https://www.mining.com/all-the-mines-tesla-needs-to-build-20-million-cars-a-year/
Institute for Energy Research, Nov. 12, 2020, The Environmental Impact of Lithium Batteries, https://www.instituteforenergyresearch.org/renewable/the-environmental-impact-of-lithium-batteries/
February 15, 2021
Where Does This Stuff Come From?
My previous blog posts discussed minerals that are either single elements or
are compounds of multiple elements. By human standards, the Earth is very
large, 5.9724 x 10^24 kg
So where did this stuff come from?
At one time, most people were satisfied with a supernatural explanation, God or The Gods were responsible for creating the Earth and everything in it. For people with more important things on their minds, like survival, it was good working hypotheses. However, some people still asked questions and the answer to the question "where does this stuff come from" eventually was found through one of our oldest scientific pursuits - Astronomy.
The systematic study of the stars probably goes back far in
the human past. However, it wasn't until
the 20th Century that we were able to build instruments that could look deep
into the far reaches of the Universe.
The discovery of other galaxies by Edwin Hubble in 1925 was followed a
few years later by his announcement that the these galaxies were in fact,
moving away from each other
Working back from the observed expansion of the Universe led
some people to postulate a "Big Bang"
Not quite. Work by
physicists looking at the physics of the fundamental particles of matter
Galactic cosmic ray reactions:
Be & B as well as some isotopes of H, He and Li
Dying low mass stars:
Some isotopes of most elements except for Be, B, Tc, and Pm
Exploding massive stars:
Some isotopes of most elements except for H, Li, Be, B, Tc, and Pm
Exploding white dwarf stars:
Some isotopes of Si, S, Ar, Ca, Ti, V, Cr, Mn, Fe, Co, Ni and Zn
Merging neutron stars:
Some isotopes of Nb, Mo, Ru, Rh, Pd, Cd, In, Sn, Sb, Ce, W and Re
Radioactive Decay of other Elements
The decay of radioactive isotopes produces numerous elements, most of them unstable. He and Ar are the most common stable elements produced by radioactive decay of other elements. All isotopes of Tc and Pm are radioactive and decay into other elements.
Figure 1, below, graphically shows the origin of the various elements
So How did this Stuff Form the Earth?
Between the time of the Big Bang, approximately 13.7 billion
years ago
We are made of star dust.
References
Williams, D. R., Nov. 2020, Earth Fact Sheet, NASA Goddard Space Flight Center, https://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html
The Physics of the Universe, 2021, The Expanding Universe and Hubble's Lawhttps://www.physicsoftheuniverse.com/topics_bigbang_expanding.html
The Physics of the Universe, 2021, The Big Bang and the Big Crunch, https://www.physicsoftheuniverse.com/topics_bigbang.html
Weinberg, S, 1993, The First Three Minutes: A Modern View of the Origin of the Universe, 2nd ed., Basic Books, New York NY
E. Casuso and J. E. Beckman, Jan. 1997, Beryllium and Boron Evolution in the Galaxy, The Astrophysical Journal, Volume 475, Number 1, https://iopscience.iop.org/article/10.1086/303503/meta
Kobayashi, C., A. I. Karakas, and M. Lugaro, June 2020, The Origin of Elements from Carbon to Uranium, Astrophysical Journal, The Astrophysical Journal, Volume 900, Number 2, https://arxiv.org/abs/2008.04660
Cosmos, Sept. 2020, Origin of the elements reviewed, https://cosmosmagazine.com/space/astrophysics/origin-of-the-elements-reviewed/
February 8, 2021
Iron and the Great Oxygenation Event
Figure 1 - Iron Forge
"Forge" by arbyreed is licensed with CC BY-NC-SA 2.0. To view a copy of this license, visit https://creativecommons.org/licenses/by-nc-sa/2.0/
Iron in History
Last week's blog entry finished with the Bronze Age collapse. Following the Bronze Age ca. 1200 B.C., historians generally place the beginning of the Iron Age.
One of the earliest known uses of iron was a dagger made for
Pharaoh Tutankhamen and buried in his tomb 1. Elsewhere
in the Near East, there is evidence of experimentation
with iron as early as 3,300 B.C., but it
was during the period following the end of the Bronze Age, ca. 1200 B.C. that
iron production gradually developed
In modern times, iron is built into the fabric of our society. From household appliances, to steel framed buildings, to bridges, to motor vehicles, to railways and ships, iron (and its alloy, steel) is used in massive quantities by modern civilization. The use of iron, and its production, is therefor one of the marks of the Industrial Age.
Producing Iron
Producing iron from iron ore is essentially a process of
chemical reduction whereby the iron ore, largely some form of iron oxide, is
heated with a carbon source, such as coked coal, and a flux, such as limestone
Figure 2 Banded Iron Formation, Soudan, Minnesota
"Jaspilite banded iron formation (Soudan Iron-Formation, Neoarchean, ~2.722 Ga; Stuntz Bay Road outcrop, Soudan Underground State Park, Soudan, Minnesota, USA) 31" by James St. John is licensed under CC BY 2.0
Banded Iron Formations and the Great Oxygenation Event
The most common source of iron ore nowadays is from banded
iron formations. Banded iron formations
are biochemical precipitates consisting of layers of iron rich sediment interbedded with siliceous
material. Most of the banded iron
formations in the world were deposited during the Great Oxygenation Event at
the beginning of the Proterozoic Eon, 2,460
to 2,426 million years ago
The Great Oxygenation Event was a time in the history of the earth when cyanobacteria (a.k.a. blue green algae) evolved photosynthesis and began releasing free oxygen into the atmosphere . The basic story is that the free oxygen combined with the dissolved iron in the ocean leading to the deposition of banded iron formations.
Sounds about right, doesn't it?
The problem is in the details of the mechanism of deposition. Was the deposition biological or abiotic? Where did the iron come from? What about all that silica, how did it get
there? What was the exact mechanism for deposition of the iron and silica?
One of the problems is that there are no modern analogies to
the late Archean, early Proterozoic environments. We are trying to understand what happened in the
shift from a reducing environment to an oxidizing environment on a planetary
scale. Clearly the banded iron
formations record a dramatic shift in the Earth's environment, but the details
are still under investigation
Jelte P. Harnmeijer of the University of Washington
concluded that "I can only say that the guy responsible for the cliché:
“what you don’t know can’t hurt you” probably came up with it after a long and
unhappy life spent attempting to understand Banded Iron-Formations"
There is a good video on YouTube from December 2020 called How Bad Was the Great Oxygenation Event that's worth watching for an easy summary of the events of late Archean and early Proterozoic eons. also, if this subject intrigues you, follow up on the references below.
References
1. Comelli, d. et al, May 2016, The meteoritic origin of Tutankhamun's iron dagger blade, Meteoritics & Planetary Science, Vol. 51, Is. 7, July 2016, pp.1301-1309, https://onlinelibrary.wiley.com/doi/full/10.1111/maps.12664?dom=pscau&src=syn
2. Erb-Satullo, N.L., 2019, The Innovation and Adoption of Iron in the Ancient Near East. Journal of Archaeological Research Vol. 27, pp. 557–607, https://doi.org/10.1007/s10814-019-09129-6
3. Chakrabarti, D.K., 1992, The Early Use of Iron in India, Oxford University Press, Oxford U.K.
4. Young, S.M.M. et al, 2019, The Earliest Use of Iron in China, in Metals in Antiquity, Oxford: Archaeopress, pp. 1-9., http://donwagner.dk/EARFE/EARFE.html
5. Cunliffe, B. W., 2008, Europe Between the Oceans, Yale University Press, New Haven CT, pp. 270 - 316
6. Colligan, E., 2017, Thule Iron Use in the Pre-contact Arctic, Ph.D. dissertation, City University of New York, https://academicworks.cuny.edu/gc_etds/2342/
7. LibreTexts, Aug.2020, Iron Production, https://chem.libretexts.org/Bookshelves/Inorganic_Chemistry/Modules_and_Websites_(Inorganic_Chemistry)/Descriptive_Chemistry/Elements_Organized_by_Block/3_d-Block_Elements/1b_Properties_of_Transition_Metals/Metallurgy/The_Extraction_of_Iron/Iron_Production
8. Wikipedia, 2021, Bog Iron, https://en.wikipedia.org/wiki/Bog_iron
9. K.A. Evans K.A., et al, Feb. 2013, Banded iron formation to iron ore: A record of the evolution of Earth environments?, Geology, Geology, 41(2)pp. 99- 102, https://www.researchgate.net/publication/256199273_Banded_iron_formation_to_iron_ore_A_record_of_the_evolution_of_Earth_environments
10. Gumsley, A. P. et al, Feb. 2017, Timing and tempo of the Great Oxidation Event, Proceedings of the Natural Academy of Sciences of the United States of America, vol. 114, no. 8, pp. 1811–1816 https://www.pnas.org/content/114/8/1811
11. Weiqiang Li, Brian L. Beard, and Clark M. Johnson, 2015, Biologically recycled continental iron is a major component in banded iron formations, Proceedings of the Natural Academy of Sciences of the United States of America, vol. 112, no. 27, pp. 8193–8198, https://www.pnas.org/content/112/27/8193
12. Harnmeijer, J.P., Mar. 2003, Banded Iron-Formation: A Continuing Enigma of Geology, University of Washington, https://web.archive.org/web/20060908034327/http://earthweb.ess.washington.edu/~jelte/essays/BIFs.doc
February 1, 2021
Copper, Tin, Bronze and the Bronze Age
Copper and tin are significant metals both in current use and in history. Alloying nine parts copper with one part tin makes bronze, an extremely useful metal. The discovery and use of bronze defined an important stage in the human story that we now call the Bronze Age.
Below, I'll briefly describe the geology of copper and tin deposits and then talk about the Bronze Age.
Copper Geology
Copper is sometimes found in nature as native copper but
more often as a component of the sulfide mineral, chalcopyrite. Weathering of chalcopyrite can lead to the
formation of minerals such as chalcocite, bornite, djurleite, malachite,
azurite, chyrsocolla, cuprite, tenorite, and brochantite.
Copper ores are found in a variety of geological
environments. Chalcopyrite is usually
found in volcanogenic environments, such as porphyry copper deposits. Weathering and/or diagenesis
of the volcanogenic rock can lead to the concentration of copper minerals in sedimentary and metamorphic rocks.
Tin Geology
The primary ore of tin is the mineral cassiterite. Cassiterite is an oxide of tin and is considered
to be part of the rutile group. Cassiterite
is formed in very light coloured (highly felsic) granites and in pegmatitic
veins. Erosion of these rocks leads to cassiterite
accumulating in placer deposits. These
placer deposits are a major source of tin.
The Bronze Age
The use of copper preceded the use of bronze. People
began using copper as early as the sixth millennium B.C. By 5,100 B.C. Copper mining was under way in what is now
Bulgaria and Spain. Copper from these
locations was traded throughout Europe.
Around the same time that people in Europe were experimenting
with copper, native copper was being mined in the Upper Peninsula of Michigan and traded throughout the eastern woodlands of
North America.
The idea of alloying copper with other metals
probably occurred to many artisans in many places. The earliest bronze appears
to have been made in what is now Serbia, during the 5th millennium B.C. ; from there the use
of bronze spread to Egypt by 3,100 B.C., and to China by 3,000 B.C
Figure 1 shows what casting bronze looks like.
Figure 1 Bronze Casting,
Credit: Hans Splinter "bronze casting (1)" by hans s is licensed with CC BY-ND 2.0. To view a copy of this license, visit https://creativecommons.org/licenses/by-nd/2.0/
During the Bronze Age, warrior elites monopolized the use of
bronze for weapons and armour. These
elites took over existing states and helped form new ones in the Middle East,
Greece and East Asia. Warrior elites
armed with bronze also dominated the chieftainships that existed outside the
civilized states. Bronze became an
important commodity in the trade networks.
For example, a flourishing trade network developed among the states of the
Eastern Mediterranean, with all sorts of goods travelling from Egypt to the
Levant, Anatolia, Cypress and Mycenaean Greece
The Bronze Age marked a great advance in the human story. It was a violent time. They weren't making weapons and armour just for show. Bronze Age states and minor polities engaged in wars from as far west as the British Isles to the Far East of Shan Dynasty China.
The end of the Bronze age was also marked by violence. The
famous siege of Troy, immortalized in Homer's epic poem, The Iliad, was only
one of many violent incidents at the end of the Bronze Age. It is more than just a story of "those
who live by the sword shall perish by the sword". The end of the Bronze Age around the year
1,200 B.C. appears to have been a
systemic collapse caused by multiple social, political and ecological factors
Systemic collapses usually begin with a ecological stress, such as bad weather that leads to crop failures. The population that could be sustained in the good times is now too big to be fed by the resources available during lean years . Consequently, a series of bad harvests will lead to social and political stress. Political and economic relationships will be tested and many will fail. Long established networks of trade may collapse as the goods that were to be traded are no longer available and the trust that bound the system together evaporates. Ambitious warlords arise who motivate desperate people to join them in raiding supposedly richer neighbours. The onslaught of armed migrants leads to the collapse of now fragile political structures. After the dust settles, the fires burn out and the bodies buried, a new dark age begins and the survivors find new ways to live.
It's happened before, don't think it can't happen again.
For further reading, begin with the references listed below.
References
Mineralogical Society of America, 2021, Important Ore Minerals http://www.minsocam.org/msa/collectors_corner/article/oremin.htm
Toutelot, E. B., & J. D. Vine, 1976, Copper Deposits in Sedimentary and Volcanic Rocks, Geological Survey Professional Paper 907-C, United States Geological Survey, https://pubs.er.usgs.gov/publication/pp907C
Stanton, R. L., 1972, Ore Petrology, McGraw Hill Book Company, Toronto ON
Cunliffe, B. W., 2008, Europe Between the Oceans, Yale University Press, New Haven CT
Cullen, K.M., 2006, Milwaukee Public Museum, Old Copper Culture, https://www.mpm.edu/research-collections/anthropology/online-collections-research/old-copper-culture
Vuckovic, Jan. 2021, The Bronze Age - A Spark That Changed the World, https://www.ancient-origins.net/history-important-events/bronze-age-0013179
Cline, E. H., 2014, 1177 B.C., the Year Civilization Collapsed, Princeton University Press, Princeton NJ
Chew, S. C., 2007, The Recurring Dark Ages, Altamira Press, Toronto ON
January 25, 2021
Platinum Group Metals
Introduction
In this week's blog, I am going to discuss platinum and the platinum group metals (PGM). PGM are generally considered to be platinum, palladium, rhodium, ruthenium, iridium, and osmium. These metals tend to occur together in nature and have similar physical and chemical properties.
PGM elements are
rare. The Earth’s upper crust contains
only about 0.0005 part per million (ppm) platinum and less of the the other PGM. Ores that are mined for PGM typically contain 5 to 15 ppm of PGM.
While PGM occur as native metals, they also occur as mineral
compounds with other elements such as copper, iron, mercury, nickel, silver, bismuth,
lead, and tin, antimony, arsenic, tellurium, selenium and sulfur. More than 100
minerals contain one or another PGM as an essential element. Native PGM usually
occur as alloys of platinum, iron, osmium and/or iridium.
PGM have many uses:
· In automobiles: pollution control catalyst, spark plugs, engine control sensors, airbag initiators, electronics for engine management systems, and fuel cells for electric vehicles
· In electronics: Connectors, Printed Circuits, Resistors, Capacitors, Lasers
· In computer hard discs, a thin layer of PGM is used to increase memory storage capacity
· In jewelry and non circulating coinage
· In glass fibre, display glass, optical glass, ceramic glass, tableware decorative patterns and finishes
· In health care for antitumor drugs, implants, treatments for heart disease, cancer screening, dental inlays, crowns and bridges
· In petrochemicals, as catalysts for production plastics, polyester, pharmaceutical ingredients, high octane gasoline, fertilizers and explosives, and silicones
·
In turbine blades for aircraft engines
Occurrence and Production
PGM can be found in:
· Magmatic intrusions i.e. mafic and ultramafic intrusions;
· hydrothermal deposits;
· sedimentary deposits;
· residual deposits from weathering; and
·
placer deposits.
Figure 1 shows the worldwide distribution of magmatic PGM deposits
Figure 1 - PGM Intrusive Deposits
World production Figures are shown on Table 1:
Platinum as Money
Like gold and silver, many people look to buying platinum
both as an investment and a store of value.
Current prices for platinum are in the order of 1,100 USD/oz. Over the past year, the prices have ranged
from a low of 588 USD/oz in March 2020 to a high of 1,119 USD/oz at the end of
the year.
As a precious metal, platinum could be used as money,
although it lacks the traditional authority of gold and silver. Imperial Russia issued platinum coins for general circulation from 1825 to 1845
One interesting tale about platinum coins began in 1992 in
the United States with a presidential candidate for the Populist Party, Bo
Gritz. Mr. Gritz proposed that the American Congress should authorize the US
Treasury to mint platinum coins in large
denominations in order to pay off the US national debt. In May 2010, a web blogger, Warren Mosler,
writing under the nom de plume of
Beowulf, popularized the idea and the Nobel Prize winning economist Paul
Krugman endorsed it in January 2013.
The idea has generally lost favour as people realized that while it may be legal, it amounts to no more than a shift of the debt from one set of financial instruments to another, i.e.from government bonds to government minted coins. Regardless of the financial legerdemain, the debt is still there.
References
Zientek, M.L., Loferski, P.J., Parks, H.L., Schulte, R.F., and Seal, R.R., II, 2017, Platinum-group elements, chap. N of Schulz, K.J., DeYoung, J.H., Jr., Seal, R.R., II, and Bradley, D.C., eds., Critical mineral resources of the United States—Economic and environmental geology and prospects for future supply: U.S. Geological Survey Professional Paper 1802, p. N1–N91, https://doi.org/10.3133/pp1802N
The International Platinum Group Metals Association, 2017, Production and Uses of Platinum Group Metals, https://ipa-news.com/assets/sustainability/IPA_Guidance/Chapter%203_PGM_Guide.pdf
U.S. Geological Survey, January 2020, Mineral Commodity Summaries, Platinum Group Metals, https://pubs.usgs.gov/periodicals/mcs2020/mcs2020.pdf
Kitco, January 2021, Live Platinum Price, https://www.kitco.com/charts/liveplatinum.html
Vasilita, S, 2020, History Russian Platinum Coins, Coins Auction, https://www.coins-auctioned.com/learn/coin-articles/history-russian-platinum-coins
Wikipedia, January 2021,Trillion-dollar coin, https://en.wikipedia.org/wiki/Trillion-dollar_coin
January 18, 2018
Gold, Silver & Money
In this blog I will discuss the precious metals, gold and silver, where they occur, how are they produced and the issue of whether or not they can still be considered money.
Gold Occurrence
In nature, most gold (Au) is almost always found as either native gold or as part of a naturally occurring alloy such as the gold/silver alloy called electrum. Gold rarely forms compounds with other elements; the twenty or naturally occurring compounds that contain gold are relatively rare.
Gold deposits are found as either:
Lode deposits such as native gold in quartz veins or disseminated gold in sulfide deposits
Placer deposits where the gold is found as either dust or nuggets.
1
Gold is extracted from placer deposits using mechanical extraction techniques, such as panning and sluice boxes, to concentrate the gold and other dense minerals. The gold is then removed from the concentrate using chemical extraction techniques.
Separating gold from a lode deposit begins with pulverizing the ore in a mill, followed by mechanical separation of a concentrate containing gold and other dense materials. The gold is then separated from the concentrate using chemical extraction techniques.
The extraction techniques used for gold concentrates from
either placer or lode deposits often include the use mercury or cyanide. (A good summary can be found in the
Encyclopedia Britannica entry on Gold Processing
Silver Occurrence
In addition to native
silver (Ag) there are about 143 minerals that have silver as a significant
component
Silver- bearing minerals are usually found in locations associated with past magmatic activity and/or hydrothermal activity. Deposits of significant grade are formed in four genetic groups:
volcanogenic massive sulphide deposits,
sedimentary exhalative deposits
lithogene deposits, and
magmatic-hydrothermal deposits.
5
In the Americas, silver deposits are commonly found along the trend of the western Cordillera from the Andes
Mountain Range to Mexico, the United States, Canada and Alaska. In Europe there is a similar trend of current
and ancient volcanic activity that passes from Spain in the west into Turkey in
the east.
Because
silver is mostly produced as a by-product of other metallic mineral production,
the methods for extracting silver from the ore will depend on the primary
metals in the deposit. Generally, the
ore will be crushed and then smelted and/or chemically treated to separate the
silver from the other constituents in the ore. (A good summary can be found in
the Encyclopedia Britannica entry on Silver Processing
Is it Money?
The use of gold and silver as currency for trade appears to have begun about 5,000 years ago in Mesopotamia. Until the middle of the twentieth century, gold and silver were normal parts of the money supply. Gold was often used to settle large, especially international accounts and silver was used in everyday coinage. After the United States went off the gold standard in 1973, most other nations followed suit. Similarly, in the latter half of the 20th century, silver coins were gradually replaced with coins made out of base metals such as nickel. Silver dollars were last issued in Canada for normal circulation (as opposed to collectors items) in 1967. It appears that the story of gold and silver as money is over.
Or s it?
Our current system of money can best be described as a consensual hallucination in that we all agree that these pieces of paper, book-keeping entries and computer algorithms are worth something. The value of our money is intimately connected to the power and authority of the governments that issue the currency and decree its value by fiat. But what happens if trust in the consensual hallucination of fiat currency fails?
Many people who keep gold and silver do so as a hedge against currency instability. Often you will hear them make the following claim:
"Gold is currency of kings, silver is the currency of free men, barter is the currency of peasants and debt is the currency of slaves."
The thinking goes that if the value of fiat currencies drops too much, then gold and silver will be the only acceptable currency. The problem with this line of thinking is that currency instability is often accompanied by social and political instability. Ultimately, the value of money depends on the stability of the community that maintains the consensual hallucination, i.e. that links "money" to the value of things we objectively need or want such as food, clothing, shelter, transportation, fuel and social status.
We may want to ponder the fact that one of the reasons we know a lot about Roman currency is that when the Western Roman Empire was falling apart, wealthy families buried their hordes of gold and silver. After the barbarians war bands came and went, many of the owners of the buried treasure did not, or could not, return to retrieve their stashes, as in Figure 1.
Figure 1 - Roman silver coins
The day may come that gold and silver will again be used as money in response to social and political instability and/or a collapse of trust in government sponsored fiat currency. Hopefully, it won't be accompanied by the return of barbarian war bands and a new Dark Age.
References
King, H. M., 2020, Gold, Mineral Properties and Geologic Occurrence, in Geology.com, https://geology.com/minerals/gold.shtml
Hoffman, J.E and A. Tikkanen, 2008, Gold processing, Encyclopedia Britannica, https://www.britannica.com/technology/gold-processing
Hudson Institute of Mineralogy, 2020, The Mineralogy of Silver, https://www.mindat.org/element/Silver
King, H.M., 2013, Silver, in Geology.com, https://geology.com/minerals/silver.shtml
Graybeal, F. K. and P.G. Vikre, 2010, A review of silver-rich mineral deposits and their metallogeny, Society of Economic Geologists, https://pubs.er.usgs.gov/publication/70194333
Hoffmann, J.E.,2015, Silver processing, Encyclopedia Britannica, https://www.britannica.com/technology/silver-processing
Karasavvas, T., October 2017, Huge Hoard of Ancient Roman Silver Coins Worth £200,000 Found During Treasure Hunt, Ancient Origins, https://www.ancient-origins.net/news-history-archaeology/huge-hoard-ancient-roman-silver-coins-worth-200000-found-during-treasure-021639
January 11, 2021
Deep Time
One of the great contributions by the Science of Geology to our collective store of knowledge was the discovery of "deep time". The story of the discovery of deep time is fairly complex, involving many people and their work, rivalries, mistakes and the lesson of all their effort. Keep that in mind when reading the brief summary below.
From their study of geology, James Hutton and Charles Lyell both recognized that the earth was probably very old; they just couldn’t find the evidence to give a definitive age
The flaw with Lord Kelvin’s estimate, made in 1863, was that it did not take into account the heat from radioactive decay. The discovery of radioactive elements by Marie Curie in 1898 lead to further investigations into radioactive minerals by many other researchers. Thousands of research papers have resulted in an accumulation of knowledge; this in turn has lead to the current estimate that the earth is approximately 4.54 billion years old
A Very Long Time
4.54 billion years is an immense period of time. To visualize it, imagine a line where every millimetre (mm) represents a thousand years and every metre (m) is a million years. On this scale, the line representing the total age of the earth will be 4,540 m long. 4,000 m (4 km) of the line represents the length of the Precambrian. The next 540 m represents the Phanerozoic Eon, the age of complex life. Approximately 252 million years ago, 252 m on the time line, the Paleozoic ended with the Permian mass extinctions. 66 m from the present on the time line, the Cretaceous ended with the K/T mass extinction. The entire existence of Homo sapiens, 300,000 years
Really makes you feel important doesn’t it?
It gets worse, the fossil evidence indicates that most of the species that have ever lived have gone extinct and there is no reason to believe that humans are exempt from this fate
A graphical portrayal of the geological time scale from The Geological Society of America is shown below
Living with the Facts
If we hope to benefit from science, then we should adopt an attitude of radical realism. From our understanding of deep time a couple of lessons stand out:
We are the heirs of an immensely long history of life, that history is rich, complex and we are part of it.
We are not as important as we would like to think we are and that is a good thing.
In the end, we are left to ponder lessons of deep time.
References
Gould, S. J., 1987, Time's Arrow, Time's Cycle: Myth and Metaphor in the Discovery of Geological Time, Harvard University Press, Cambridge MA
Lamb, E., June 2013, Lord Kelvin and the Age of the Earth, Scientific American, https://blogs.scientificamerican.com/roots-of-unity/lord-kelvin-age-of-the-eart/
United States Geological Survey (USGS), July 2007, Age of the Earth, https://pubs.usgs.gov/gip/geotime/age.html
Science News, September 2017, Modern humans emerged more than 300,000 years ago new study suggests, https://www.sciencedaily.com/releases/2017/09/170928142016.htm
Quora, March 2015, Why do scientists think that over 99 percent of all species that ever lived have gone extinct?https://www.quora.com/Why-do-scientists-think-that-over-99-percent-of-all-species-that-ever-lived-have-gone-extinct
The Geological Society of America, Aug. 2018, GSA Geologic Time Scale, Version 5.0, https://www.geosociety.org/GSA/Education_Careers/Geologic_Time_Scale/GSA/timescale/home.aspx