Tuesday, November 19, 2019

Geology Through Literature - The Periodic Table

Geology Through Literature: The Periodic Table

The Periodic Table was a rich experience with the author, Primo Levi, recounting several stories within his life through the framework of elements on the Periodic Table, hence the name of the book. But here we are interested in the "geology" through literature, not chemistry, so what does this book have to offer us? Quite a bit actually. Here are some of the more geological sections.

First Chapter - Argon
"...[this] Piedmontese dialect, never written except on a bet, and the Hebrew inlay, snatched from the language of the fathers, sacred and solemn, geologic, polished smooth by the millennia like a bed of a glacier."
Although there are known instances where glaciers have moved quickly, they are generally known to have a slow pace to them. Hence the term "glacial" meaning slow. But over time, as the glacier moves, the base of the glacier defrosts and refreezes continually. This defrosting and freezing causes the base of the glacier to pick up various pieces of rocks, gravels, sand, and rock powder. These pieces of the landscape are then forced downwards by the weight of the overlying ice, which can sometimes reach many miles in thickness. These rock pieces, that are being forced downwards as the glacier moves forward, have the effect of acting like sandpaper on the surface of the Earth, slowly polishing the bedrock smooth. Over time that smoothness is ground down finer and finer. This polishing effect also produces powered rock known as glacial flour, just like sandpaper does to a piece of wood.

Sixth Chapter - Nickel
"Yes, all mines are magical per se, and always have been. The entrails of the earth swarm with gnomes, kobolds (cobalt!), nickel, German 'little demon' or 'sprite,' and from which we derive the word nickel, creatures who can be generous and let you find a treasure beneath the tip of your pickax, or deceive and bedazzle you, making modest pyrites glitter like gold, or disguising zinc in the garb of tin: and in fact, many are the minerals whose names have roots that signify 'deception, fraud, bedazzlement.'"
This passage is interesting because it touches on a couple of different aspects of minerals. One is their sometimes resemblance to other, more or less important minerals. And the other is the naming of the minerals, which sometimes goes so far back in history that their original names don't have any direct correlation with what they are known for today.

Visual comparison of Pyrite to Gold from GeorgiaGold.Com
One of the most commonly misidentified minerals would probably be pyrite for gold. Pyrite, often known as "fool's gold", has a strong gold colored metallic luster to it, where people are immediately drawn to assume it is gold.  Pyrite is actually a fairly common mineral, especially when compared to the far more valuable and elusive gold. Pyrite is made up of iron and sulfide (FeS2), while gold is just made up of elemental gold (Au). The name "Pyrite" comes from the Greek word "Pyr", which means "fire". The name comes from the fact that when it was struck with an iron tool back in ancient times it emitted sparks.

The mineral cobalt. From Mining.com.
The name of the mineral cobalt originally came from the German word for goblin or devilish spirit, kobold.  Around 1500 AD (BCE), German miners were mining for silver when they came across this substance, which looked like silver but did not act like silver. And to top it off, when they tried to melt it down it gave off noxious fumes, which caused the miners to get sick and sometimes die. They attributed it to goblins having bewitched the silver ore causing the noxious fumes. One of the problems was that the primary metals known at the time: gold, silver, copper, iron, tin, lead, and mercury,  were the only known metals since ancient times and the miners had no concept that new metals could even exist. In the 1730's a Swedish chemist, Georg Brandt, was able to isolate the metal and ended up using the same name that the German miners had branded it with.

A small chunk of nickel from Live Science. 
In the 1600's the Germans were at it again. This time miners were searching for copper and came across this brownish-red rock that they believed was copper. However, when they tried to extract the copper from the rock they were unsuccessful. They ended up blaming "Nickel" for the lack of copper, who was a mischievous German demon. They called the ore kupfernickel, which means "copper demon". In 1751, another Swedish scientist, Baron Axel Fredrik Cronstedt, was able to extract the nickel from the kupfernickel ore, which was a mixture of arsenic and nickel. He ended up dropping the first part of the name and kept the "nickel" part as the name of the element and mineral. 

Eighth Chapter - Mercury
"That very evening just before nightfall, we heard a great rumble of thunder, as though the island itself was being shaken to its roots. In a few minutes the sky darkened and the black cloud that covered it was lit from below as by a fire. From the top of Mount Snowdon we saw first rapid red flashes leap out and climb up into the sky, then a broad, slow stream of burning lava: it did not descend toward us but to the left, the south, pouring from ridge to ridge, hissing and crackling. After an hour it reached the sea and there it was doused with a roar, lifting up a column of vapor. None of us had ever thought that Mount Snowdon could be a volcano; and yet the shape of its summit, with a round hollow at least two hundred feet deep, could have made us us suspect this. 
The spectacle continued all through the night, calming down every so often, then picking up again with a new series of explosions; it seemed that it would never end. Yet, toward dawn, a hot wind blew from the east, the sky cleared off again, and the uproar gradually died down until it was reduced to a murmur, then silence. The mantle of lava, which had been yellow and dazzling, turned reddish like smoldering coals, and by daylight it was extinguished."
Map of Desolation Island highlighting Mount Snowdon from The Periodic Table
Unfortunately,  Desolation Island, and the mysterious volcano Mount Snowdon, were both made up for the story. I had hopes that they would really exist given the autobiographical nature of the rest of the story, however this chapter was one based entirely in fiction. The original Mount Snowdon, the one from which the story's volcano was named, was formed during the Ordovician period (450 million years ago) along a prehistoric convergent plate boundary in what is now Whales. A convergent plate boundary is when one plate was forced down underneath another plate. This caused the lower plate (the one going down into the Earth) to melt. The liquid rock, magma, then slowly rose over time and ended up forming volcanoes, like the aforementioned Mount Snowdon (the real one). The real Mount Snowdon however has long been an extinct volcano and has been eroding ever since.
Simplified map of the Mediterranean plates showing the subduction zones. From Ring et al, 2013
Although it is never spelled out, there are a couple of locations for which the island could be located. One of those is the Mediterranean based on the eruption style. Within the Mediterranean you have an over abundance of islands, many of which are either volcanoes or volcanic in origin. This is because you have the same situation as the formation of Mount Snowdon (the real one). There are numerous subduction zones, creating numerous volcanoes across the region, specifically in Italy and Greece. These volcanoes form as the subducted plate starts to melt and that melted plate material, the magma, rises up through the crust. Eventually, as more and more magma builds up, the pressure builds up and the volcano erupts. When the magma moves through continental crust it picks up more silica based minerals, which melt at a lower temperature and produce more explosive eruptions, like the ones seen from Mount Vesuvius. The story of Mount Vesuvius/Pompeii is very reminiscent of the story that Levi told in the The Periodic Table with lava and ash clouds erupting from an unknown volcano.

However, Levi points out at the beginning of the chapter that Desolation Island is located 1,200 miles to the southeast from an island known as St. Helena. St. Helena is actually a real volcanic island that is located in the middle of the southern Atlantic Ocean. It's claim to fame is that it was the location of Napoleon's final exile/imprisonment and where he eventually died. Although the island is a volcano, it's last eruption was 7 million years ago, when the island was situated along the Mid-Atlantic Ridge. The Mid-Atlantic Ridge is a divergent plate boundary, which means that two plates are pulling apart from each other. This pull-apart results in a very long volcanic mountain chain located beneath the oceanic surface. While most of the volcanoes remain below the surface of the ocean, some do break the surface, with St. Helena being one of those examples. Eventually the island moved along with the plate as the plate spread out from the divergent plate boundary. This movement moved the volcano away from its source of magma, making it an extinct volcano, likely never to erupt again. The type of eruption that came from St. Helena would be vastly different than the one from Pompeii as well. While Pompeii would contain an explosive eruption with lots of ash and volcanic gasses and clouds, St. Helena would more resemble a Hawaiian eruption, with a steady stream of low-viscosity lava and very little clouds.

Ring, U., Gessner, K., Thomson, S., & Markwitz, V. (2013). Along-strike variations in the Hellenide Anatolide orogen: A tale of different lithospheres and consequences. Bulletin of the Geological Society of Greece47(2), 625-636.

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