THE MARCASITE GROUP OF MINERALS

The Marcasite Group is composed of minerals with a similar orthorhombic structure and related chemistry. It is named for its most common member, marcasite. The general formula for this group is AX₂. The A can be either iron, cobalt, nickel, osmium, iridium and/or ruthenium. The X can be either sulfur, arsenic, selenium and/or tellurium. Marcasite's formula is FeS₂ for example. The members of the Lollingite Group are sometimes placed in the Marcasite Group. Marcasite is the only common member of this group.

• Anduoite (Ruthenium Osmium Arsenide)
• Ferroselite (Iron Selenide)
• Frohbergite (Iron Telluride)
• Hastite (Cobalt Selenide)
• Iridarsenite (Iridium Ruthenium Arsenide)
• Kullerudite (Nickel Selenide)
• Marcasite (Iron Sulfide)
• Mattagamite (Cobalt Telluride)
• Omeiite (Osmium Ruthenium Arsenide)
• The Lollingite Group:
  • Costilbite (Cobalt Antimonide Sulfide)
  • Lollingite (Iron Arsenide)
  • Nisbite (Nickel Antimonide)
  • Rammelsbergite (Nickel Arsenide)
  • Safflorite (Cobalt Arsenide)
  • Seinajokite (Iron Nickel Antimonide Arsenide)