Finding specimens is not that hard or inaccessible if you are determined. Virtually any place on earth has its own geomorphology history. Start by looking at geological maps to learn what kind of rocks/minerals you can find in your surroundings and look for old/active mines, quarries or any activity that excavates soil, etc. Specimens can be found sometimes in land deposits from these activites.

We used to have asbestos rocks sitting around in our house when I was growing up (my mother was born a raised in the town formerly called Asbestos, QC). You could just peel the fibers off the rock. In that form the asbestos is harmless: it's only when it's chopped into shorter fibers and inhaled that it's seriously unhealthy. Industrial uses almost always chopped the fibers so almost no commercial products using asbestos are safe, but the rocks just sitting there are harmless.

I am sure there is a great list somewhere of places to see stuff like this (or I can ask an LLM), but I can vouch for

Mines Museum of Earth Science (Golden CO) and The Harvard Museum of Natural History (Mineralogy room, Cambridge MA)

If you happen to be in Hilo, HI, the Lyman Museum is pretty cool too.

True, but among the minerals with cubic crystal structure it is not unusual for them to be found as crystals that are perfect regular or semiregular polyhedra, with a shape characteristic for the mineral, for instance octahedron (e.g. spinel, diamond), rhombic dodecahedron (e.g. garnet) or cube (e.g. pyrite).

I suppose that the crystals from the picture are of pyrite, which frequently looks like this.

In the antiquity, when what are now called diamonds (the Romans and the Greeks called them "Indian adamants", because they were first encountered by Europeans during the expedition in India of Alexander the Great; "adamant" meant something else in Europe) were very difficult to cut and polish, they were normally used as gems in their natural shape of regular octahedra.

Cutting diamonds from their natural octahedral shape into polyhedra with more facets, e.g. brilliant, was invented much later.

That’s what really sucks about rockhounding as a hobby. In the US we have a blessing of public BLM lands where we can collect, especially in the West, but most of the interesting specimens in museums and fancy collections come from mines or some unique geological occurrence on private land. Getting them requires dropping lots of money or getting into commercial mining. The best most of us can really hope for is some small piece from tailings.

There are a few species you can sometimes find in washes when they get buried during massive floods, but other than that most museum quality specimens are impossible to find for rockhounds.

I still bring my trusty Estwing rock hammer everywhere but it kind of takes the wind out of the treasure hunting aspect.

Central California has several abandoned asbestos mines which continue to release asbestos into the nearby air and water. I remember considering some hiking around the area once and then came across the warnings regarding exposure.

CA also has a lot of naturally occuring mercury as well. I seem to remember that some lakes in CA are so high in natural(i.e. not from gold mining) mercury that you shouldn't eat the fish.

Second the Rice Museum recommendation! If I ever make it big I'm going to legally change my last name to 'Mineral' and create the Mineral Museum of Rice on the other side of the freeway showcasing everything from basmati to risotto.

Maybe try copper sulphate?

https://crystalverse.com/best-way-to-grow-copper-sulfate-cry...

Crystal growth has been on here before. Let me see if I can find a link or two...

https://news.ycombinator.com/item?id=31105320

https://news.ycombinator.com/item?id=30487511

https://news.ycombinator.com/item?id=29779923

https://news.ycombinator.com/item?id=29255511

Pyrite or fool's gold, lovely mathematical perfection and a great etymology to match!

> There are a few species you can sometimes find in washes when they get buried during massive floods, but other than that most museum quality specimens are impossible to find for rockhounds.

Well, that's kinda how it has to be, right? If art museums displayed the artwork anyone can paint, they wouldn't be interesting to most people. Most museums are about displaying the stuff you otherwise wouldn't be able to find, buy, or make. It's still fun to learn to paint, even if you're no Rembrandt.

To be fair, there are some museums that go for depth instead of scarcity and I personally find them more interesting. The Computer History Museum does this pretty well. They have some truly unique items, but also plenty of stuff you can buy on eBay, just presented and explained well.

I live in the northeast USA, there are very few public collecting spots around me. It makes me really sad listening to people who have been in the hobby for a long time talk about all the amazing collecting sites they used to frequent before they were paved over with parking lots or condominiums and whatnot. There isn't a whole lot of "wild open space" left around here to poke about in. Another big factor for keeping the public out of collecting sites that do still exist is that some people can't be bothered to be respectful in their collecting.

The Loudville lead mine in Easthampton MA, which used to be open for public collecting, recently closed due to irresponsible collecting and severe erosion. They closed off the entire recreational trail system, which has far reaching affects far beyond the rockhounding community.

I'd collected once at Loudville shortly before it closed and found a couple scraps of Pyromorphite, some tiny Wulfenite you need a microscope to see, and some Malachite. I am sad that I can't go back, now.

You can read more about it here: https://newenglandforestry.org/newsroom/recreation-on-the-ro...

I don't expect, or really even want to find museum-quality specimens, I just want the ability to explore the minerology of my home region on a physical and personal level.

The Monte Cristo basin in Washington is high enough in Arsenic that you shouldn't drink water there. There are warning signs at trailheads EG the trailhead leading into Gothic Basin and Gothic Peak.

"The best most of us can really hope for is some small piece from tailings."

Just this past weekend I pulled a plate full of rare tellurides out of Otto Mountain for a Caltech PhD. You have to be very observant to find a good spot to acquire minerals out of the ground, but excellent large specimens are still out there to be pulled.

This makes me want to find an actual rice museum that isn't the IRRI.

There are several different kinds of asbestos and they differ radically in their level of risk and the worst kinds are not (generally?) found in California. So that signage might just be out of an abundance of caution.

I wouldn't be surprised if by the numbers you have a lot more risk of serious injury driving to and from the hike than from the asbestos, particularly if your hiking doesn't involve intentionally disturbing the ground. :)

For the many posters on HN in the bay area-- watch road cuts for green rocks, asbestos co-occurs with serpentinite all over the coast range-- and serpentinite is the state rock! You can easily find some with asbestos, usually grey/white fibrous strands on the rocks. Don't grind it up and huff it, but you can thrill your friends by showing them some boogieman-mineral you found.

(It's only fitting that the state rock is technically known to the state of california to cause cancer... :P)

I did that with my kids and it was pretty cool !

I agree. Here are a few more nice images for the GP: https://www.google.com/search?q=pyrite+cube&tbm=isch Remove "cube" from the reach, to see the not cubic samples too.

Especially since it's an exception that breaks the rule that straight lines are not found in nature. Not only is it a straight line, but a cube. They just look unnatural. Very cool stuff

That pyramid shape in the amethyst is what grabbed me. Looks like something straight out of a video game. Incredible.

What about organic mishmashes that are shaped into cubes?

https://www.science.org/content/article/how-do-wombats-poop-...

> Truly a hidden gem

Where the gems are in plain sight!

Terra Mineralia in Freiberg (quite close to Prague), is also worth a visit.

Regarding etymology, for many centuries the substances that are now called "sulfides" were called "pyrites", after the "iron pyrite" i.e. the iron (II) disulfide, which is the most abundant sulfide mineral.

At the end of the 18th century, Lavoisier together with a few other French chemists have created the modern systematic chemical nomenclature, so the old term "pyrite" was replaced by "sulfide" (like also "vitriol" was replaced with "sulfate").

For who does not know, "pyrite" comes from "fire", i.e. from the pronunciation in Ancient Greek of the corresponding word that was cognate with English "fire" (Ancient Greek or Latin "p" corresponds with English "f").

Striking pyrite produces sparks, which can be used to start a fire.

You can buy pyrite cubes on Etsy—I know because I also love them :)

They’re not expensive

The religious have managed to make every YouTuber say "gosh" though.

> Ancient Greek or Latin "p" corresponds with English "f"

Similarly, ancient Greek "p" corresponds with modern Greek "f", and ancient Greek "b" corresponds with modern Greek "v".

We may have done it first, but the sound change is pretty common. "B" -> "v" is arguably in process in Spanish. Something similar had already happened in Latin; compare Latin "frater" to English "brother" or Latin "fero" to Greek "phero".

And Galena! Another wonderful metallic mineral that forms cubes.

So many people carry this dull heavy just in their pockets to fend off all attempts to revive the sense of wonder they buried deep in their childhood.

For me, just the very fact that there exist time, space, laws of physics, enormous complexity stemming from deceptive "simplicity", is absolutely awe-inspiring.