Calcite
Image: <a href="//commons.wikimedia.org/w/index.php?title=User:Hapecko&action=edit&redlink=1" class="new" title="User:Hapecko (page does not exist)">Jan Pavelka</a> (CC BY-SA 4.0)
Mineral NameCalcite
Chemical FormulaCaCO3
Mohs Hardness3
Crystal Systemtrigonal
Lustervitreous
Streak Colorwhite
Cleavageperfect rhombohedral on three directions
Fractureconchoidal
Specific Gravity2.71
Colorscolorless, white, yellow, pink, blue, green, brown, black
Transparencytransparent
Type LocalityWorldwide (e.g., Iceland for optical grade, various localities for aesthetic specimens)
Mineral GroupCarbonates
Usescement production, building material, optical instruments, soil treatment, chemical industry, collector specimens
Associated Mineralsquartz, fluorite, barite, pyrite, galena, sphalerite
Raritycommon
Description
A block of calcite, appearing blue due to a laser beam passing through it, demonstrating fluorescence where some blue light is absorbed and re-emitted as orange light.
Geological Context
Calcite is a common mineral found in sedimentary rocks (limestone, marble), metamorphic rocks, and hydrothermal veins. It is the primary component of shells and skeletons of many marine organisms.
