Mineral, MnCO3; sp. gr. 3.4–3.7; hardness 3.5–4.5; trigonal; translucent rose-pink, and sometimes light grey to brown, developing a brown or black crust on exposure; white streak; vitreous lustre; crystals rare, but form as rhombohedra, and rod-like and curved, but it is usually massive or granular; cleavage perfect rhombohedral; occurs in hydrothermal veins containing silver, lead, and copper, and in metamorphic and metasomatically altered rocks of sedimentary origin, often a secondary mineral after manganese oxide; soluble, with effervescence, in hot, dilute hydrochloric acid. It is used in the manufacture of ferromanganese, being added to blast-furnace charges, and in the chemical industry.