magnesiitti

Magnesiitti, known in English as magnesite, is a mineral consisting of magnesium carbonate, MgCO3. It belongs to the carbonate mineral group and crystallizes in the trigonal (rhombohedral) system. Pure magnesite is white and translucent, but impurities can give gray, yellow, or brown hues. It typically occurs as euhedral crystals or massive deposits and has a vitreous to resinous luster. It hardness is about 3.5–4 on the Mohs scale and the specific gravity is around 3.0. Magnesite effervesces in dilute acids such as hydrochloric acid.

Magnesiitti forms by metamorphism and metasomatism of magnesium-rich carbonate rocks, such as dolostone, and by high-temperature hydrothermal activity. It is commonly found in hydrothermal veins and in contact metamorphic zones and is often associated with dolomite, calcite, quartz, serpentine, and talc.

Economically, magnesite is the principal source of magnesium carbonate and is mined in several countries for industrial use. Major applications include the production of magnesium oxide (MgO) after calcination, which serves as a refractory material in steelmaking, cement kilns, and other high-temperature environments. Magnesium carbonate derived from magnesite is also used as a filler in paints, plastics, and ceramics, and, in some cases, as a nutritional supplement or antacid.

Global deposits are distributed worldwide, with major sources in China, Slovakia, Turkey, Austria, Greece, Iran, and Russia. Smaller but important occurrences are found in the Czech Republic, India, the United States, and Canada. Environmental considerations include land use from mining and CO2 emissions associated with calcination in MgO production.