Calcite
Image: Robert M. Lavinsky (CC BY-SA 3.0)
Mineral NameCalcite
Chemical FormulaCaCO3
Mohs Hardness3
Crystal Systemtrigonal
Lustervitreous
Streak Colorwhite
CleavagePerfect rhombohedral in three directions at 74° and 106°
Fractureconchoidal
Specific Gravity2.71
Colorswhite, colorless, gray, yellow, pink, green, blue, brown, black
Transparencytransparent
Type LocalityIraí, Alto Uruguai region, Rio Grande do Sul, Southern Region, Brazil
Mineral GroupCarbonates
Usescement production, construction aggregate, soil conditioner, optical instruments, acid neutralization, jewelry (rarely)
Associated Mineralsquartz, fluorite, barite, pyrite, galena, sphalerite
Raritycommon
Description
This image displays a well-formed, transparent to translucent, colorless rhombohedral crystal of calcite, exhibiting its characteristic perfect cleavage and vitreous luster.
Geological Context
Calcite is a ubiquitous mineral, forming in various geological settings including sedimentary rocks (limestone, marble), hydrothermal veins, and as a secondary mineral in igneous and metamorphic rocks. It is the primary component of shells and skeletons of many marine organisms.
