What is "magnesite"

Magnesite \Mag"ne*site\, n. [Cf. F. magn['e]site.] (Min.) Native magnesium carbonate occurring in white compact or granular masses, and also in rhombohedral crystals.

n. (context mineralogy English) A form of magnesium carbonate, magnesiumcarbonoxygen₃, occurring as dolomite (with calcite) but rarely found in the pure state.

n. a black magnetic mineral consisting of magnesium carbonate; a source of magnesium

Magnesite is a mineral with the chemical formula Mg C O ( magnesium carbonate). Mixed crystals of iron(II) carbonate and magnesite (mixed crystals known as ankerite) possess a layered structure: monolayers of carbonate groups alternate with magnesium monolayers as well as iron(II) carbonate monolayers. Manganese, cobalt and nickel may also occur in small amounts.