[Iwonda (OP)]

If you pulverize a pyrite crystal and add a strong acid, what type of a reaction should you get ?

[paul cotter]

I am not quite sure but it is NOT a good idea. Pyrite is iron disulphide and although I have never considered such a reaction there is a strong possibility of forming the highly toxic gas hydrogen sulphide. Iron sulphide and a strong acid is a standard lab method of producing this gas while the action of acid on pyrite should in theory produce H2S2, a liquid at STP. Very late addition: it appears H2S2 will disproportionate in aqueous media to H2S and S so this would be a very bad idea. Hydrogen sulphide(H2S) is a pernicious substance in that exposure, although it stinks, poisons the olfactory system and after a short while it cannot be smelled even when one is exposed to a lethal concentration. 

[Iwonda (OP)]

I totally agree with you about acid and pyrite being a bit dangerous but all of the test that I did were on a very small scale. I was curious about a tiny cluster of crystals; I thought that they might be sperrylite, so someone recommended that I do some acid testing. It turns out that they were just pyrite but, the acid test results were very, very strange. I got a lot of strange things that grew out of the acid solution. I saw what look like spheres, fibers, dendrites and even a host of isometric shapes that would precipitate out of the solution. It made for some really neat art like photos.

[Bored chemist]

Sperrylite is interesting (and very rare).
A compound of platinum- which you want and arsenic which you don't want.
 What you want to be very careful about is not converting it to arsine.

[paul cotter]

Yes, arsine would be even more hazardous than hydrogen sulphide. Curious as to it's odour, as the hydrides of many non metals smell bad I looked it up in Wikipedia where they state it is pyrophoric, in which case one would never smell or inhale it. I find this to be dubious but my Cotton&Wilkinson does not mention such a property. I will look it up in my Mellor when I get the time.

[Iwonda (OP)]

In trying to figure out if this was pyrite or sperrylite, I had read that if you heat up pyrite and smell it, you should get that rotten egg smell of sulfur. I heated it and took a good smell at least three time but did not smell anything. I had contacted a scientist, sent him some close-up photos of the matrix and I told him about the smell test that I had done. He asked if I would give him a call, said that he had something very important to share with me. I was a bit reluctant to call someone that I met on the web, but I was desperate for answers, so I called him. The first thing out of his mouth was, "why aren't dead"?

[paul cotter]

Well, we did warn you against doing such things. One should never add strong acid or heat to a mineral sample unless one has all the necessary ppe and a decent fume hood and don't sniff anything! I looked up arsine in my copy of Mellors inorganic chemistry and I find it is not pyrophoric and it does smell bad. It killed two early researchers, A F Gehlen and M Bullacker. 

[Iwonda (OP)]

It wasn't the acid testing that made this stone dangerous to heat and sniff. He had notice in the close-up photos of the stone that it had a good amount of the mineral realgar mixed in the matrix. Realgar is an arsenic sulfide and just a tiny amount of this stuff heated up and inhaled can kill. He also highly recommends that I wash my hands good after handling this stone. I thanked him very much for the call and the info and told him that I was going to hang up and then go throw up  .