Carnelian
Image: Shannon Heinle (CC0)
Mineral NameCarnelian
Chemical FormulaSiO2
Mohs Hardness7
Crystal Systemtrigonal
Lustervitreous
Streak Colorwhite
Cleavagenone
Fractureconchoidal
Specific Gravity2.58
Colorsyellow, orange, reddish-orange
Transparencytranslucent
Type LocalityIndia, Brazil, Uruguay, Germany, USA
Mineral GroupSilicates
Usesjewelry, decorative objects, carvings, collector
Associated Mineralsagate, chalcedony, quartz, calcite, zeolites
Raritycommon
Description
Carnelian is a translucent to opaque, reddish-orange to yellow-orange variety of chalcedony, which is a cryptocrystalline form of quartz. It often exhibits a waxy luster and is commonly found as tumbled stones or polished cabochons.
Geological Context
It forms in silica-rich solutions within cavities of volcanic rocks, such as basalt, where it precipitates as microcrystalline quartz, often in banded layers. Its characteristic color is due to the presence of iron oxide impurities.
