Mineral, FeS2; sp. gr. 4.8–4.9; hardness 6.0–6.5; orthorhombic; pale bronze-yellow; greyish-black streak; metallic lustre; crystals tabular and spear-like, but it is also massive, stalactitic, and radiating; cleavage {101}; occurs in low-temperature mineral veins together with zinc and lead ores, and in sedimentary rocks, especially limestone, chalk, and clay. It has been used in the production of sulphuric acid. Compare pyrite.