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High Quality Copper Content

@cufes2

Geologist, Metallurgist, and Avid History Nerd Blog for my long-form academic interests

So part of my research is looking at trace element variations in chalcopyrite. Of the given ones on the right, there's a lot of variation in quantities of tin, silver, arsenic, gallium, and uh-

Zinc, as it so happens.

No idea what's happening at Walker Mine. I need to dig a little more into it today. We also have a few more Walker Mine mounts in the making to learn more.

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I'm continuing to read about alum and it's honestly fascinating how the concept of money, commodities, and power, shifts from culture to culture.

Europe had no silver circa 500-1500 AD. It was primarily exported in from Africa and through dealings with Persia, along with the Crusades. But throughout this time, the Catholic Church was still rich and powerful, and you have all the general European bickering at the time. If hacksilver was so common and valuable metal so rare, and defrauding so common, where were displays of wealth going?

Textiles.

The pope(s) used an effective monopoly on alum to wield power throughout Europe, threatening everyone who tried to mine their own alum with excommunication. After 1486, because England had no laws on the books to support the papal alum monopoly, they became a smuggling center, waylaying Spanish ships with Spanish alum by using the papal law to uphold the monopoly, then "commandeering" the alum cargo since it was now under English rule, and England had no legislative obligation to give it back to Italy, it was now theirs and could be used for English trade.

This was, obviously, extremely lucrative.

In 1503 the pope raised the price of alum, driving the Hapsburgs into (illegal) trade with England. They helped commission two massive Tudor gunships with the concession England supply them with alum. However, as this was going on, only the crown was able to sell alum and Henry VII fined private merchants and confiscated alum not brought by his own ships or from Tolfa, Italy. This netted him even more profit.

The pope(s) were obviously less than thrilled about this, and cut Henry VII out of their most recent crusading plans, as well as temporarily retracing their papal ambassador. Henry VII did not stop though, and set his son, Henry VIII up for stunning economic success.

... which he promptly squandered by restarting alum purchases from Italy, allowing them to boycott alum sales to England when his excommunication came due.

But all in all, there's this FASCINATING hole of economic history in alum that feels completely ignored! We think of pre-Renaissance era as (or, to be clear, I was taught that-) the pre-Renaissance era was a time of mostly miserable raids and crusading. Everyone was bickering for a seat at the table; there were a lot of popes and a lot of power-grabs. But the available commodity that was changing hands in Europe was alum and most of the power was tied up in paper and textiles.

We think of textiles as work that's been overshadowed since it was done by women, but it's not just that: it's economic power has been overshadowed too. When we see "yard of wool", we should still be thinking of all the processes and industry that went into dying that material, and alum is fundamental to that trade. England's power grew on their wool industry and alum privateering. Spain's influx of silver came from their colonies- but they also were part of England's back door alum trade that allowed the rest of Europe to slip from the church's grasp.

Mounier, Aurรฉlie, and Florรฉal Daniel. โ€œSome Papal Bull: 16th Century Alum Trade and English Royal Autonomy.โ€ Summer Research, 2020, 379.

Gรผnster, Andrea, and Stephen Martin. โ€œA Holy Alliance: Collusion in the Renaissance Europe Alum Market.โ€ Review of Industrial Organization 47, no. 1 (August 2015): 1โ€“23. https://doi.org/10.1007/s11151-015-9465-0.

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I'm so tired of finding cool papers that I want to read but have no time or energy to fall down the rabbit hole.

Hell yes I want to compare Scottish and English wool trade from 1300-1600 but I came here just for a map or numeric value/conceptual analysis of the textile trade in England at the time pre-Henry VII and I'm ready to fall over actually.

If anyone is interested, here's the alum presentation~

The desert has mushrooms!!!!

(Left) Battarea phalloides or saprophytic sandy stiltball. The sandy stiltball appears quickly following rains, most often in loose sandy soil such as that found around washes.

(Right) Podaxis pistallaris or the desert shaggy mane. Appears following rains and seems able to thrive in the most impossibly arid and barren spaces, even growing on top of anthills. Desert shaggy mane is found in deserts around the world including Africa, Australia, the Middle East, and North America.

(Left) Astreus hygrometricus, or the hygroscopic earthstar. Ectomychorrhizal: it attaches itself to the outside of tree roots in a mutually beneficial partnership where the tree provides the fungus with carbon and the fungus provides the tree with moisture and soil nutrients. This is a great trade for desert trees who are constantly searching for moisture in our dry soils.

(Right) Agaricus deserticola, does not develop true gills, but rather a convoluted and networked system of spore-producing tissue called a gleba. When the veil breaks or pulls away from the stem the blackish-brown gleba is exposed, which allows the spores to be dispersed. Fruit bodies grow singly or scattered on the ground in fields, grasslands, or arid ecosystems.

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I don't want to respond to the direct post, 1) because the vote is over and it passed, 2) because I don't feel like being thorough about my commentary which means asking friends of friends at the site and looking up papers and permits. But holy cow, it keeps popping up on my dash.

1) Copper mines do not produce toxic waste. If anyone is telling you this, they're lying to you or stretching the truth, max.

1.2) If you leave a hole in the ground alone for long enough, the sulfides in the rock oxidize and produce a weak to strong acid that leaches metals. That's what they're talking about. This does not happen to active mine sites because the water in the tailings/waste is reused and must be near-neutral. Calcium is also added to neutralize the acid. When the mine is shut down, when properly closed, all surfaces are covered so this oxidation can't take place.

2) Mining on the Michigan peninsula is one of the few places we have records of pre-Columbian copper use because the copper is in native form. It's very disingenuous of them to not mention this. See here.

3) Tailings dam specifications are built with geology in mind. They're huge. I don't think people understand how big (or small) they actually can be. But essentially, the engineering specs reflect the regional qualifications of the dam. A 100-year flood build design likely reflects the overall dam but not a location near a drainage basin which would be certified to higher spec. I worked at a mine that was near a fault and the qualifications were 1.2+ factors of safety over the shake potential for that kind of fault zone. Which is how it works for all engineering designs. The design plans would not have gotten this far in the USA without three licensed engineers looking at the plans.

Anyway. Don't lie to people right over my salad. It's absolutely okay not to want a mine in your backyard. There are actual reasons to get up in arms if you feel that way. But lying to people is not the way to do it.

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โ™ ๏ธ How strange is it for Ea-Nasir to have kept so many of his complaints? A large part of the hearstory about Ea-Nasir here on tumblr is that the room of tablets of complaints he kept was abnormal, with the usual inference being that he was an egotistic scoundrel reveling in the displeasure of his clientele.

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I'm sorry for taking so long to answer this question! I thought it would be much easier to answer than it was, haha.

This is the original archaeologist, Woolley's, original map (left), from Woolley, 1931. I've overlain the map with different colors (right), (mine) to hopefully alleviate confusion. [1]

What is known as Ea-Nasir's house, is called No. I Old Street (Grey). The main entrance is Grey-Room 1, which opens to an open courtyard. Grey-Room 5 and Grey-Room 6 both contain altars. Grey-Room 4 is small, beneath a staircase, and contains a drain. The courtyard also contains a drain and a earthen "box" near a kitchen area in Grey-Room 7. The only definitive context we have for a tablet addressed to Ea-Nasir is the one found near this box, in the doorway between Room 2 and 7. [2]

Tablet 16089a (or UET V 29) reads: "Speak to Ea-Nasir: Thus says Muhaddum with regard to the ingots: the sealed tablet of your companions has just 'departed' to you. Now Saniqum and Ubaiatum have gone to come before you. If you are truly my brother, send somebody with them, and the ingots which are at your disposition may be given to them." [translation: Leemans, 1960] [3]

The lack of definitive context is due to lack of cards and Woolley's need to fire the tablets before their reading/publishing [4]. Either the cards were actually lost, or, potentially, misattributed due to the amount of damage to Straight Street No. III (yellow) [5]. If you look up the descriptions of tablets mentioning Ea-Nasir [6], by name on UrOnline, most of them say, "House IV/Old Street No. I".

So that said, there are several notable features of No. I Old Street (grey) and No. III Straight Street (yellow)'s formal house descriptions [7].

  1. Grey-Room 5, Grey-Room 6, and G-Y-Room 10 are all altar rooms. Typically, each house has one altar room. Two is unusual. Three is extremely strange.
  2. No. I Old Street (grey) is extremely old, and the walls stayed relatively consistent.
  3. The long Grey-Room 3 hallway originally connected to the purple and red rooms houses, but these were sold and bricked off.
  4. No. III Straight Street (yellow) was "much ruined" and consistently remodeled, also younger than the boundary walls of Church St. No. III (orange) and Straight St. No. V (teal) [5, 2].
  5. The half-walls of Yellow-Room 13 acted as three open sheds. Yellow-Room 9 was a kitchen, Yellow-Room 3 was a stairwell and drain, and Yellow-Room 4 was a bedroom. The door between the courtyard (Y-2) and "guest room" (Y-G-6) was larger than usual too, and the wall was built with brick mud and matting between the bricks to give a thick structure, unusual in private buildings.
  6. Yellow-Grey-Room 10 was another altar with an incense room and chimney behind it (Y-G-11).
  7. The position of the rooms with drains, G-2, G-4, Y-G-5, and Y-3 are all near altars or kitchens, including G-2 which is near the kitchen of G/Red-7.

Overall, even though Ea-Nasir's tablets might have been found here (which we can't be sure of, because the cards have been lost or misattributed), I think the shape, age, and abnormality of "Ea-Nasir's House" is important. None of the rooms in grey were described as or seem to be a bedroom, excepting the rooms that were sold and bricked off (red and purple).

Straight St. No. III that does seem to function as a house (kitchen, drain, second story, bedroom), clearly has access to the altars but with separation between them.

Because of the lack of tablet context and general abnormality, I don't think this means Straight St. No III was Ea-Nasir's house or he was an altar-keeper. Y-G-6, G-3, Y-8, or the upper floors could be used for tablet storage, but Woolley doesn't mention caches of tablets (or fallen tablets) in either location, while he does for No. VII Church Street (red) [8]. If the cards are misattributed and "House IV" means "House III" or another location, then we also have to reconcile the artifacts at that location which might have nothing to do with Ea-Nasir, or are also missing their artifact cards. And other than finding the cards, we might never know.

So at the very least, from the previous write-up, where Ea-Nasir is a man working closely to the temple, prioritizing the state's copper over private business orders, I think the little context we do have reflects that. That one tablet is not in an unusual location- It was delivered to the step of a religious area where the message would either be kept or eventually given to its intended recipient.

References below the cut:

Came across this while looking for info on Ea-Nasir for something school related (donโ€™t question it). Overall this research is really excellent work, though I wonder if anyone has ever re-examined Woolleyโ€™s room identifications. (One of my professors used to bring up that someone needed to do that for Minoan room identifications, as Arthur Evans was known to just kind of say things based on vibes. Iโ€™m paraphrasing slightly.) But Iโ€™m willing to accept those for the sake of this discussion.

What I do question is this part of the conclusion: โ€œThat one tablet is not in an unusual location- It was delivered to the step of a religious area where the message would either be kept or eventually given to its intended recipient.โ€ I donโ€™t think we should call the tablets location the place that it was โ€œdelivered to.โ€ This is Ur, not Pompeiiโ€”the building wasnโ€™t evacuated in a hurry with everything left as it was. The tabletโ€™s location then is either where it was stored long-term, or where it was discarded.

Given that the tablet and box were found in an area that would have heavy foot traffic, I donโ€™t think โ€œstorageโ€ is the logical conclusion. If I had to guess (and this is strictly based on what you have here, I havenโ€™t looked into the reports for details), Iโ€™d say what makes most sense is that the tablet was left behind in this spot when the building was abandoned.

I donโ€™t think this undermines the rest of your answer. The grey house appears to be a public or religious building that Ea-Nasir could have worked at or with; it could be he lived in the yellow house, or perhaps the owner of the property lived there and Ea-Nasir merely worked there. I would be curious to see what other non-copper-complaint documents were found there, and what sort of business/religious model they suggest.

However, I do think the fact that the grey building was effectively a place of business is important. As such, its administrators (Ea-Nasir himself, his accountant, etc) likely kept records of business transactions. A letter such as this could be taken as proof of payment received, or of the names of business contacts, or something similar. (Obviously speculation, but my point is that this doesnโ€™t seem an unusual thing to keep in the files.) The letters of complaint could have been stored for similar reasons, or out of a need for a โ€œcomplete record,โ€ or even in case of a lawsuit. That would have been a thing in ancient Ur, and I have a feeling Ea-Nasir was familiar with the process.

However, as I said, clearly these letters werenโ€™t stored on the floor of the courtyard by the door to the kitchen. And as funny as the image of Ea-Nasir decorating the wall of his place of business with negative reviews is, I think the more likely explanation is that whenever the building was abandoned (because Ea-Nasir died, or the business went under, or the roof started leakingโ€”whatever the reason), the old records were sorted through, some to keep and some to discard. Iโ€™m a bit of a hoarder so I know what it looks like when I move out of a placeโ€”clay tablets everywhere. (Hey mom do I still need these pay stubs fromโ€ฆ 2005?) Sadly that means the letters of complaint were definitely in the โ€œdiscardโ€ pile, or at least in the โ€œkeep but if we forget them itโ€™s not worth going backโ€ pile. Thatโ€™s what the location of the tablet suggests to meโ€”dropped or put down in the moving process and never retrieved.

Again, this is all speculation, Iโ€™ve just been eyeballs deep in Bronze Age Mesopotamia trivia for a week now (school stuff), and I needed to share at least a little.

(Also, if you want my really out there explanation for the tablets, itโ€™s that this is neither Ea-Nasirโ€™s house nor his place of business. Itโ€™s the Temple of the God of Shitty Merchants and Ea-Nasir dedicated the tablets of his worst reviews as offerings. Can I back this up in any way? No. Do I think itโ€™s hilarious? Absolutely. Will this explanation find its way into a Mesopotamian era fanfic I write? Depends if I survive the next few semesters and can ever get back to writingโ€ฆ)

My absolute favorite part of being a historical metallurgist is going back to texts like Dr. Easby here and saying, "Yeah man, this is normal. We still gotta do this part of wax casting. 'cause physics."

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Differences between pyrite and chalcopyrite? (With pictures?) ๐Ÿ‘€๐Ÿ‘€

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Initial differences: Pyrite is FeS2. Chalcopyrite (creatively named) is CuFeS2. Pyrite is an almost silvery yellow on a fresh surface; chalcopyrite is more of a bronzy yellow. The difference is subtle, but once your eye is tuned, you can almost always pick out bits of chalcopyrite in a sea of pyrite.

The cleavage of the minerals helps too: pyrite almost always breaks with glittering sharp edges unless it's pretty oxidized or weathered. chalcopyrite is rough, almost like a smear. I think it's much closer to looking like gold, than real fool's gold, tbh.

It's really hard for a camera to properly catch that glint, but I gave it a shot:

This sample is a good 50/50 Py-Cpy, and I think the portions that look smoother are simply weathering from the sample being passed around. But you can still see Py is almost... brighter. And on the left, there's a very clear crystal of straight yellow Cpy that stands out.

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I wondered if this was a tailings dam and wanted to combat the copious misinformation in the reddit comments, so I did a little digging!

The Rosia Poieni mine in Romania is owned by the Romanian Government, operated by CupruMin S.A., started by the communist party in 1978 and ongoing today. It's a Copper open pit mine producing copper concentrate, using the flotation method, which is generally environmentally neutral and causes minimal damage; which makes this pond... unusual. I also realized the poster didn't know what he was talking about because he kept saying cyanide leaching. This is neither a leach heap, nor cyanide-prominent because sulfuric acid is the most common byproduct of copper mining, not cyanide (used for gold mining).

I initially searched for acid mine drainage from the Rosia Poieni pit and got a very helpful study from 2002 on Acid Mine Drainage into the Muscanilor brook that drains the mine site, passes their ore dump, and drains into a river further downstream. The paper details the type of minerals and alteration present at the mine (extremely helpful), and mentions that there's little to no carbonates present in the deposit, which makes it hard to neutralize the acid the mine generates.

However, this is to the south of the mine, and when I started looking at Google Maps, the laz decantare Valea Sesii is to the north. They don't process their copper concentrate onsite in their own smelter, so there was still minimal explanation for why there was so much acid in the pond. (Or what the pond was since "laz decantare" translates to decant pond in English, which is just a basin for solids to settle out.)

Searching for the smelter that processes their copper, I found the Zlatna Smelter from a USGS log. This says it's north of the mine, but Zlatna is actually south; I searched for a smelter north of the mine but couldn't find one, and in Zlatna you can see the smelter stack from the road; so I'm pretty sure this is just a typo. [Also, 45% recovery is insanely low. Even for 1992!]

So! Since the smelter (which would produce sulfuric acid) is out of the picture, we're back to wondering why this pond is so toxic.

I started doing searches on decant ponds, to see if there was a reason it was called a decant pond, and turned up a Romanian webpage from 2013 protesting the potential Rosia Montana mine. While a bit cumbersome, the pictures and write-up were the most insightful on what the hell is going on in Valea Sesii.

The Valea Sesii, via a mine contact, is an open valley tailings pond. This is Insanity #1. Tailings ponds can be acidic and it's what I thought the lake was in the first place. You usually line them, or place them on an impermeable rock/clay layer so acid doesn't leak into the water table. This valley could be on an impermeable rock layer; I don't have enough information; but it's very clear it's unlined. You also usually keep your ore and waste heaps near each other and on or close to the pond so all the acid drainage is in one spot. Their ore heap, according to the first paper, is all the way on the other side of the mine, so you have two points of drainage, and one just flows down the slope.

Insanity #2.

THEY STEPPED ON THE TAILINGS BEACH. THIS IS SUCH A BAD IDEA. I CANNOT EMPHASIZE ENOUGH HOW BAD AN IDEA THIS IS. THE FACT THEY WERE ABLE TO WALK AROUND A TAILINGS DAM OF THIS PH WITH NO SUPERVISION IS MENTAL. IT'S SO INSANE. YOU HAVE NO IDEA.

PLEASE DO NOT DO THIS. SULFIDES AND ACID DRAINAGE OFTEN CREATE A FOAM CRUST THAT LOOKS SOLID BUT IS INCREDIBLY UNSTABLE AND DECEPTIVE. THIS SAND IS ALSO <75um AND ACTS AS QUICKSAND. DO NOT WALK ON IT.

The author writes, "The tailings continue to be discharged consistently and the level of the pond rises every year. That's why the people from Cupru Min raise the dam year after year." (I still have to research Cupru Min.) But yes, this is how tailings dams work. Usually they're properly sequestered, lined, and don't eat up towns, but as tailings are deposited, they pump the largest sand grains onto a dike a few hundred feet thick and continuously deposit sand into the impoundment/valley, and the dike, keeping the water away from the dike walls. You can see this here, in the upper right corner:

Here we encounter Insanity #3 on the blog:

I cannot emphasize enough how insane this is. I'm sure they wanted to make a better way and couldn't because tailings are so unstable you can't make a path out to the deposition point, but someone has to walk out there and move these pipes, and turn them on and off manually. This picture makes me want to scream about safety. Also, let me just point out that water HAS to be a pH of <2 from the color. If someone falls in, you will be very, very badly burned. Begging whoever has to manage these pumps to be safe.

HOWEVER. None of this answered WHY the dam is so acidic if it's only used as a tailings pond, until the author reminded me, "the tailings mess is discharged through a system of pipes that ... allow the discharge to be directed to various areas on the contour of the pond."

This is also fairly normal; most mines have three to four basins they rotate deposition in, allowing them to dry out so they can compact the sand. But looking at the areas of deposition on the Valea Sesii, and putting the time into context, things make a lot more sense. Obviously this is only pieced together with my experience, pictures, and google maps, but it seems very likely.

The Rosia Poleni mine creates an incredible amount of acid due to its mineralogy and rock composition, and the rocks around it aren't able to neutralize the acid. In the 1970s, nobody cared about this, especially the USSR, and said Build It Anyway. So they simply allowed the acid to run into the valley. This is Insanity #4.

I'm sure it was either planned, or quickly realized that the acid would take over the valley, so the mine planned a dam to the northwest, and used it to contain deposition.

The tailings are from the concentrator. Concentrator tailings are usually low in sulfide content, because all the sulfides have copper and other metals, and get floated away. For example, another tailings pond I know of, with the same process as the Rosia Poieni mine, has a pH of ~6-7. (Water has a pH of 7.0.)

But their concentrator is about a mile away! They have to pump/direct their tailings sand a mile away to the pond! This, in its own way, is a minor insanity, just for the logistics. I think having your tailings pond >1mi is normal though.

And FINALLY, almost everything made sense. I would put five dollars on the acid shown in other areas of the pond being acid mine drainage pumped directly from low areas in the mine into the tailings pond. Better it go in the tailings pond than the river.

So that is the most likely operational history of the Rosia Poieni! If you're going to be angry at anyone, this mine is STATE OWNED. The Romanian government is IN CHARGE OF THIS MINE, although they do not operate it, THEY FUNDAMENTALLY PROFIT OFF OF IT. They are also allowed to MAKE THE ENVIRONMENTAL RULES. This is the downside of having state-run facilities. The government is now fundamentally a corporation and WILL NOT reign themselves in.

Now go, be free! And remember that cyanide is not used or a byproduct from copper mining, it's from gold mining.

-=-

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Instead of calling minerals normal things like "Pyrite" or "Zircon" we should say them as gross approximations of the formula like "Zrsio" or "Fes" or "Mgsiooh". This is impossible to differentiate and solves nothing.

Me changing cummingtonite and tourmaline into Mgfesiooh and Caknavaalfelimgmnalcrfevbosialboohf

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Best sedimentary rock facts?

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If you set a coal seam on fire, you get a lot of weird rare minerals from the thermodynamic reduction and high-T influx of CO2. However some are common: graphite!

Evaporite salt flats provide the Cl necessary to form massive Fe-rich Iron-Oxide-Copper-Gold deposits (IOCGs).

Dolomites can only form in areas where repetitive wave motion replaces the Mg ions with Ca ions! Some Italian Japanese geologists were finally able to replicate the process.

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Holy shit holy shit holy Schist!!!!!

A hydrothermal explosion happened Yellowstone!! And Iโ€™m alive to see it! I wish I was there.

From USGS Facebook:

A small hydrothermal explosion occurred in Yellowstone National Park today (July 23, 2024) around 10:00 AM MST in the Biscuit Basin thermal area, about 2.1 miles (3.5 km) northwest of Old Faithful. Numerous videos of the event were recorded by visitors. The boardwalk was damaged, but there were no reports of injury. The explosion appears to have originated near Black Diamond Pool.

Biscuit Basin, including the parking lot and boardwalks, are temporary closed for visitor safety. The Grand Loop road remains open. Yellowstone National Park geologists are investigating the event.

Hydrothermal explosions occur when water suddenly flashes to steam underground, and they are relatively common in Yellowstone. For example, Porkchop Geyser, in Norris Geyser Basin, experienced an explosion in 1989, and a small event in Norris Geyser Basin was recorded by monitoring equipment on April 15, 2024. An explosion similar to that of today also occurred in Biscuit Basin on May 17, 2009.

More information about hydrothermal explosions is available at https://www.usgs.gov/observatories/yvo/news/hydrothermal-explosions-yellowstone-national-park.

Monitoring data show no changes in the Yellowstone region. Todayโ€™s explosion does not reflect activity within volcanic system, which remains at normal background levels of activity. Hydrothermal explosions like that of today are not a sign of impending volcanic eruptions, and they are not caused by magma rising towards the surface.

Additional information will be provided as it becomes available.

The Yellowstone Volcano Observatory (YVO) provides long-term monitoring of volcanic and earthquake activity in the Yellowstone National Park region. Yellowstone is the site of the largest and most diverse collection of natural thermal features in the world and the first National Park. YVO is one of the five USGS Volcano Observatories that monitor volcanoes within the United States for science and public safety.

YVO Member agencies: USGS, Yellowstone National Park, University of Utah, University of Wyoming, Montana State University, UNAVCO, Inc., Wyoming State Geological Survey, Montana Bureau of Mines and Geology, Idaho Geological Survey

Image courtesy of Vlada March.

Hydrothermal explosions are the most likely of Yellowstoneโ€™s volcano hazards. Small hydrothermal explosions happen almost annually someplace in Yellowstone National Park. The least likely hazard is a major explosive eruption.

Ah! I love this video so much! Most people know Yellowstone as a volcano, but one of the fantastic things about Yellowstone, is it's one of the largest examples of a high-sulfidation epithermal system! And they're so, so, so, so cool!

So Sulfidation ore deposits all rely on three things: being close to a magmatic source, a zone of weakness for fluid to move through, and groundwater availability/chemistry. "Epithermal" is just the term for forming near the surface. High-sulfidation systems just refer to the sulfur dioxide (SO2) offgassing from the magma; the farther away from the magma, the less influence SO2 has on the system.

So in high-sulfidation systems! The SO2 reacts with water to form H2S, or hydrogen sulfide, and sulfuric acid. Now, this is the really cool part. Whenever we think of deposits, or a concentration of minerals in one area, there's always a source, a carrier, and a trap that pulls the element from solution.

For high-sulfidation systems, we have our source (the magma) and the carrier (H2S), which sometimes attach to metals and other semi-metallic ions and bring them into the fluid rising to the surface.

The catch is, water doesn't boil at high pressures. All this fluid is extremely hot, but it's deep enough not to boil. But when it reaches around 300ft, the fluid boils, the H2S and acid break back down to SO2, and everything with it is deposited at the boiling point region. The water forms Yellowstone's gorgeous pools, and the SO2 is why it smells like rotten egg!

Isn't that awesome?!

Now, to the eruption: The other super fantastic chemical property evident in high-sulfidation deposits is the solubility of carbon dioxide (CO2) in water. CO2 concentration decreases in water when the temperature rises, unlike just about every other compound. Good for carbon dioxide being unique over here~

And because CO2 doesn't like to be in solution at high temperatures, crustiform calcite (CaCO3) forms when fluid heats up. 'Crustiform' is a very specific mineral texture; it's rather irregular and bladed, generally deposited in veins. It's difficult to describe. But this form of calcite only occurs with rapid deposition, making it synonymous with boiling water.

Because of these properties, calcite builds up in areas of low pressure as water boils. And as material is deposited, less and less area is available along the fluid path, raising the pressure in the region that had been the boiling point so the fluid doesn't boil, while the ground in Yellowstone is under constant flux. All it takes is one tip of the scale, faults shift when the surface is too near, it lowers the fluid pressure quickly, and you have a marvelous unexpected catastrophic hydrothermal failure!

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wait no please explain mineral processing!!!

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I gasped in delight at the ask, haha. I love mineral processing.

Mineral processing is the theory of economically getting your desired element out of whatever it naturally comes in. So Li out of spodumene, or Cu out of chalcopyrite. It's usually split into hydrometallurgy and pyrometallurgy (liquid chemistry and melting the fuck out of it, respectively), and often taught as hard rock extraction, but you need it for Every Element, really. So you can also focus on extracting phosphates, or nitrates, or uranium! It's chemistry++~

Personally, I know the most about copper extraction and my focus is on hydrometallurgy/geometallurgy, although pyrometallurgy is near to my heart. Copper is coincidentally a really good example of how the two work because it comes as so many natural minerals. (Further explanations under the cut...)

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Do geologists just know all the rocks the same one would expect a wizard to know all the spells?

Yes. But depends how specific you want to get!

There are two kinds of rock "descriptions" when you're trying to name a rock: Rock Groups, and Rock Descriptors. Geologists often use them interchangeably, but they're very different.

Rock Groups are the overall chemical compositions of a rock that give you a ballpark idea. This is typically what people think when they say 'type' of rock and most geologists will ID it. Limestone tells you that the rock is predominantly CaCO3 and was likely formed in a shallow ocean environment. Sandstone tells you that the rock is a bunch of little sand grains.

However, this is sandstone. ^ And this is also sandstone. ^

To differentiate the two, geologists start adding descriptors. So a full "name" for a sedimentary rock might be, "Red, poorly-sorted, well-rounded quartz arenite sandstone"

Translation: A red sandstone where grains are roughly the same size, fairly round, and of primarily quartz composition.

Volcanic rocks are often much harder, because it's based on percentage of minerals in the rock. "Granite" is a rock grouping most people know, but really defines "a rock high in silica and aluminum and low in iron and magnesium with large crystals that took a while to cool." Whereas, "Basalt" would be "a rock high in iron and magnesium, lower in silica and aluminum with crystals too small to see with the naked eye that cooled quickly."

Whereas a full name would be, maybe, "Porphyryitic Granodiorite" = "rock of granodioritic composition on the diagram, with some large crystals in a fine-grained matrix". Or "Green Vesicular Propylitically-Altered Basalt" = "Green fine-grained rock with holes that had a lot of iron and magnesium but that was taken out and replaced with a lot of calcium."

You can definitely ask most geologists for the short types and groupings! But we'll take much longer to really dial in and get a good answer for specific rock types. It's hard to remember all the possible descriptors there are.

The actual science behind this was really interesting to hear but I have to say it kinda broke my mind a bit

If it makes you feel better, that's an extremely normal reaction! It peels back the sort of half-truths that we're obligated to tell people in undergrad classes/grade school because they're already overwhelmed by classifying rocks via color and context.

Igneous, Sedimentary, Metamorphic are the boxes that we put rocks in because they describe the kind of environment we're looking for. And then the first level beneath that is, (for ign.) how large are the crystals and what color is the rock; (for sed) what are the parts of the rock made of, and (for meta.) what texture is the rock?

Those classifications are more that enough to overwhelm a beginner because each answer to the question corresponds with a physical environment of the earth. You have ~roughly~ six igneous rocks to correlate, five sedimentary rocks (+/- 2 depending on how mean the teacher wants to be), and six metamorphic rocks, (also +/- 2 depending on educational cruelty).

Geology is, for this reason, the most philosophical science, because there are 'rules' to follow, in the sense that technically if you have over 90% quartz in an igneous rock, you're supposed to call it a Quartzolite. But unless you sit and count out every single fucking crystal in an 1x1 inch representative rock sample (which some people DO and I applaud them for), you don't know that it's over 90% quartz. Or a sedimentary rock might change intermittently over several meters from a sandstone to a cobblestone because it had channels running through it. What do you call the rock then? A sandstone? or a cobblestone?

It'd be sadistic to make people just introduced to the concept of time over place and "sandstones can indicate a river or a desert environment, while cobblestones can mean a river or rockfall environment" to- "you could kind of name this anything sandstoney-sedimentary; the presumed interpretation doesn't change, but add these descriptors to make sure the people who come after you know you saw these cobblestones and weren't ignoring them; or it'll chaos at the conference bar because one guy saw some angle on the cobblestones here and you didn't."

Alternatively: "The Masters Student who comes after you will be EXTREMELY happy you said the word "anoxic" about this grey stuff because it correlates to their interpretation about rocks halfway across the world which have to be correlated to what this part of the world was doing at the time."

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