What the gold rush means to most people: Prospectors! Dusty mine cars on tracks in the wild west! Gold nuggets!
What the gold rush means to an archaeologist: Hmm, where on this 100-acre plot of land covered in contaminated mine tailings do I think these clowns might have buried barrels full of literal cyanide?
How dare you leave this nugget hiding in the notes!
Why were they burying barrels of cyanide? How and why would you even compile enough cyanide to fill multiple barrels???
My friend let me introduce you to the terrifying process of cyanidation, wherein finely crushed ore containing traces of gold is made into a slurry by adding water, then transferred into vats known as “slime separators,” where potassium cyanide is then added to leach the gold into a liquid. Slaked lime is used to prevent the cyanide from going into full Murder Mode as hydrogen cyanide. The gold is then separated from the cyanide through one of a series of processes that I’m not really qualified to explain, but I think there are a few websites that talk about them if you want to google them.
But the key point here: from what I can tell, cyanide has been the main method of getting gold out of the ground for the last 120 years. (Yes, this process is still used today.) Before this technology came along, instead a thin coating of mercury was spread onto a copper plate, and the ore was allowed to wash over it. The gold stuck to the mercury, creating an amalgam, and then the amalgam was scraped off the plate and the mercury was boiled off (urk) to leave the gold behind.
And when processing mills shut down historically, why bother to dispose of your leftover deadly chemicals properly, when you can just bury them in your local tailings pile, which is already contaminated with mercury and arsenic? The known case of this happening in my local area was revealed through a bloom of “Prussian Blue” (ferro cyanide) on the surface of the tailings. Luckily, this is a fairly stable form of cyanide. Unluckily, geologists are crazier than archaeologists and they went ahead and dug a sample test unit right next to it, even knowing what it was, because science.
When I said to myself, “I’ll be an industrial archaeologist. It’ll be cool,” I did not foresee the terrifying knowledge it would unleash upon me.
I’m from Goldrush Country and I didn’t know this. All the gold-mining-related historical attractions around here are about good old-fashioned panning and pick-axes. Now I’m incredibly glad I’ve never had any urge to go explore the suspiciously colorful hills left in the wake of various mining operations.
Eek! Please don’t play in tailings piles and outflows folks, they are Bad News. “Oh but it’s lovely sand we want to take our ATVs out on it and let our kids build sandcastles” NO. DO NOT.
Reblogging because some desert-dwellers might not know this. Yes, those pretty hills are probably within ATV driving distance of Amargosa, Ocotillo, Buttercup, Superstition or whatever other recreational area you might be camped out at, but rainbow-colored dirt is usually rainbow-colored for toxic reasons!
Absolutely! And bear in mind too, not all tailings are brightly coloured - the ones in my area are just light grey. “Sand in spots where sand isn’t common” is sometimes the only warning sign.
I’m reviving this post because I’m doing up a Health & Safety protocol for digging near a mining site and folks. I did the math based on some recent soil tests. The tailings near my test site contain enough arsenic that ½ teaspoon of soil (tailings) easily contains a fatal dose of arsenic for an adult. Please stay safe and wash your hands thoroughly before eating/drinking/smoking if you aren’t 100% certain what the dirt is like where you’re digging.
And this is why we found a whole quart of mercury in my grandparent’s basement! Old timey prospectors would really just do shit.
[Image ID: Tumblr reply from highEmpressOfDirt reading: a different kind of Mine Sweeper /End ID]
This is emphatically not a desert-specific problem, just FYI. All of the contaminated mines I’ve encountered have been in spruce-dominated forests and bogs in Atlantic Canada. This is a worldwide issue.
[Image ID: A screenshot of a tag reading “#I’m nowhere near a desert but good info for those who are”]
