Pyrite Wikipedia
Pyrite enjoyed brief popularity in the 16th and 17th centuries as a source of ignition in early firearms, most notably the wheellock, where a sample of pyrite was placed against a circular file to strike the sparks needed to fire the gun.. Pyrite has been used since classical times to manufacture copperas (iron(II) sulfate).Iron pyrite was heaped up and allowed to weather (an example of an ...