The mineral pyrite, or iron pyrite, is an iron sulfide with the chemical formula FeS₂.
Pyrite is one of the most common of the sulfide minerals. It has a metallic luster and pale brass-yellow-gold hue that gives it a slight resemblance to gold. Many people often call pyrite “Fool’s Gold”.
Sometimes, pyrite is found in sedimentary rocks that contain fossils. It is believed that the creatures that become pyritized fossils were buried very rapidly in ocean sediment that was lacking in large amounts of organic matter or anaerobic sea water, water lacking in Oxygen. The pyrite would replace the organic matter. In some cases upon exposure to the air, the pyrite would begin to oxidize and “rust”.
This pyritized brachiopod is an ATRYPA measuring 1.28 inch wide and 1.17 inch top to bottom. Reverse side has only a little pyrite. Beautiful addition to any fossil collection.
Silica Shale Formation