PYRITE
Pyrite is a common iron sulfide mineral (FeS2).
It’s nickname is “fool's gold”. Pyrite has a metallic luster, brassy gold
color (in contrast to the deep rich yellow gold color of true gold), dark gray
to black streak, is hard (H=6 to 6.5), has no cleavage, and is moderately heavy
for its size. It often forms cubic crystals or pyritohedrons (crystals
having pentagonal faces).
Pyrite is common in many hydrothermal veins, shales,
coals, and several types of metamorphic rocks.
Pyrite
(5.8 cm across)
Pyrite concretion from an Upper Devonian black shale succession in Ross
County, south-central Ohio, USA (Wayne
State University collection, Detroit, Michigan, USA).