CompuServe Messages

Help — Doug, Lanny, Jerry, Nathan, Michael-if-not-left-on-vacation — everyone else: Most of you know, I'm an x-ray diffractionist. It seems I'm about to be asked to determine whether a particular scale or deposit may have caused a minor explosion. The material is allegedly an iron sulfide. (I say, "It ain't nothing till I calls it.") This is probably not a naturally-occurring material, but a corrosion product or a precipitate. I'm posting a variation of this message up in Chemistry, but thought maybe some of you with mining experience might have come across this in your travels. Here goes: I have been told that under certain conditions, "iron sulfide" will self-ignite or spontaneously ignite. What might these conditions be? Either environmental or morphological/chemical, specific to the sulfide? It seems the reaction has to do with the decomposition of the Fe-sulfide: I think oxidation of the iron, freeing sulfur which is flammable. (My boss said the *sulfur* oxidizes, but I think he mis-spoke himself, — unless he was speaking of that last spontaneous step!) Now, Hurlbut and Kline says that marcasite is less stable than pyrite — would that imply that a finding of marcasite implies potential "pyrophorism"? What about the pyrrhotites, greigite, mackinawite, or the few Fe-sulfides with no mineral name? Detectable free sulfur? Anything else you can think of? Yikes — this is almost certainly going to come my way tomorrow, so if anyone has any info on this, the sooner the better (I'll be infinitely grateful!). Thanks — E.