marcasite
marcasite 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.
marcasite
mar·ca·site / ˈmärkəˌsīt/ • n. a semiprecious stone consisting of pyrite. ∎ a bronze-yellow mineral consisting of iron disulfide but differing from pyrite in typically forming aggregates of tabular crystals. ∎ a piece of polished steel or a similar metal cut as a gem.
marcasite
marcasite XV. — medL. marcasīta — Arab. marḳašīṯā — Pers. marḳašīšā; assoc. with -ITE.