kalsiittin

Kalsiitti, known in English as calcite, is a common carbonate mineral with the chemical formula CaCO3. It is the most stable polymorph of calcium carbonate at Earth’s surface and occurs in a wide range of geological environments. Calcite crystallizes in the trigonal crystal system and often forms rhombohedra; its habits range from granular to massive and sometimes clearly crystalline. A distinctive property is strong double refraction, especially noticeable in clear varieties such as Iceland spar, which is used in polarization experiments. Calcite forms widely in sedimentary rocks like limestone and dolostone, but also in metamorphic marble and in hydrothermal veins. It is a major constituent of cave features such as stalactites and stalagmites.

Physically, calcite has a Mohs hardness of about 3, perfect rhombohedral cleavage, and a specific gravity around 2.71. It has a vitreous luster and can be transparent to translucent. Calcite readily effervesces in dilute acids, releasing carbon dioxide. Its color ranges from colorless and white to various shades of yellow, pink, green, or brown due to impurities.

Calcite is economically important as a source of lime and cement, formed by processing limestone. It is also used as a filler in plastics and paper, as an additive in paints, and as a mineral of optical and decorative interest. In geology, calcite helps identify and interpret sedimentary processes and diagenetic histories, and its occurrence in caves provides clues about karst systems.