magnesitt

Magnesite, known as magnesitt in Norwegian, is a mineral and chemical compound with the formula MgCO3. It is the principal mineral form of magnesium carbonate and belongs to the carbonate minerals. Magnesite crystallizes in the trigonal crystal system and commonly occurs as white to colorless crystals or in massive, granular material. Impurities can impart gray, yellow, or brown hues. It has a vitreous to pearly luster and a white streak.

Formation and occurrence: Magnesite forms in sedimentary and metamorphic settings through diagenetic alteration of magnesium-rich limestones and dolostones, and in some hydrothermal environments. It is commonly associated with dolomite, calcite, quartz, and serpentine and occurs in regions with high-magnesium rocks. Economically viable ore bodies occur in primary magnesite deposits and metamorphosed carbonates.

Physical properties: Magnesite has a Mohs hardness of about 3.5–4 and a specific gravity around 3.0. It is typically white or colorless, but may appear gray, yellow, or brown due to impurities. It is translucent to opaque and effervesces in dilute acids.

Uses: The principal use is as a source of magnesium oxide (MgO) after calcination, serving as a refractory material for kilns and furnaces and as an additive in cement. Magnesite is also milled for pigment and filler applications and, in some cases, used to produce magnesium metal. It is valued as a mineral specimen and decorative stone.

Distribution: Significant magnesite deposits are exploited in several countries, including China, Turkey, Slovakia, and Spain, with other sources worldwide. The ore is typically mined by open-pit methods and processed to remove impurities before calcination.