Pyrite on Rhyolite

Pyrite—also known as iron sulfide—is a prime commercial source of both sulfur and iron, and is highly coveted by collectors due to its lustrous, cubic, and complex modified crystals.

Rhyolite is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained in texture, but may be porphyritic, containing larger mineral crystals, as seen with the pyrite crystal in the specimen offered here.