What is "creedite"

n. (context mineral English) A monoclinic-prismatic mineral containing aluminum, calcium, fluorine, hydrogen, oxygen, and sulfur.

Creedite is a calcium aluminium sulfate fluoro hydroxide mineral with formula: CaAlSO(F,OH)·2(HO). Creedite forms colorless to white to purple monoclinic prismatic crystals. It often occurs as acicular radiating sprays of fine prisms. It is translucent to transparent with indices of refraction of n = 1.461 n = 1.478 n = 1.485. It has a Mohs hardness of 3.5 to 4 and a specific gravity of 2.7.

Creedite was first described in 1916 from the Creed Quadrangle in Mineral County, Colorado. It is a product of intense oxidation of ore deposits.