Magnesite (Carbonate)

MgCO3

Hardness: 3.5 - 5
Specific Gravity: 3.0

Characteristics: Solid solution exists between magnesite and siderite; usually white, gray or yellow; vitreous luster; transparent to translucent; sometimes fluoresces; denser than calcite or dolomite, two related minerals; will not effervesce with HCl.

Found in hydrothermal deposits in peridotites and other ultramafic igneous rocks; pegmatites; serpentinites; talc schists; limestones; dolostones.

Magnesite is the principle ore of magnesium which has a broad range of uses such as fertilizers, medicines, fireworks, car rims, and the tiles of the space shuttle.

(Primary text: Perkins, D. 2002. Mineralogy. Prentice Hall.)