This week’s image comes to you from a display of minerals at the University of Denver’s Olin Hall — it’s a sample of Pyrite:
Also known (if not loved) as “fool’s gold,” it’s an iron sulfide — actually, the most common of the sulfide minerals. And surprisingly enough, it’s been both a blessing and a curse.
On the bad side of things (aside from the confusion factor for would-be gold hunters), pyrite oxidizes fairly rapidly when exposed to humidity. This is a prime cause of acid mine drainage (a big problem in areas with old, inactive mines), and can cause spontaneous combustion in coal mines with high-sulfur coal seams. Meanwhile, pyrite’s oxidized products take up greater volume than its unoxidized form, helping cause mine collapses.
On the positive side of the ledger, pyrite has many potential uses. It’s been a commercial feed stock for production of a number of useful chemicals, is still used in hobbyists’ “crystal radios,” and can be used to make low-cost photovoltaic solar panels.