MarcasiteFeS2
Class: Sulfide Hardness: 6 - 6.5 Density: 4.9 Streak: Grayish black Lustre: Metallic Habit: Acicular aggregate Colours: Bronze-yellow, darkening on exposure | | Crystal System: Orthorhombic Cleavage: Distinct Fracture: Uneven Magnetism: None Reaction with HCl: Very weak | Identification in hand sample: Bronze-yellow colour and habit are indicative. Streak is also helpful. Associations: Common in hydrothermal sulfide deposits, generally formed at low temperatures. Industrial / ecomonic uses: Can be used as source of sulfur and iron, but not normally economically valuable. Comments: Polymorph of pyrite |