Quartzite
Image: James St. John (CC BY 2.0)
Mineral NameQuartzite
Chemical FormulaSiO2
Mohs Hardness7
Crystal Systemtrigonal
Lustervitreous
Streak Colorwhite
Cleavagenone
Fractureconchoidal
Specific Gravity2.65
Colorspink, red, white, gray, purple
Transparencytranslucent
Type Localitycity of Sioux Falls, Transcontinental Arch, southeastern South Dakota, USA
Mineral GroupSilicates
Usesconstruction material, decorative stone, abrasives
Associated Mineralsquartz, muscovite, feldspar, garnet
Raritycommon
Description
A blocky, angular piece of fine-grained, pinkish-red quartzite, displaying a somewhat sugary texture from its interlocking quartz grains.
Geological Context
This Paleoproterozoic Sioux Quartzite, dating 1.65 to 1.70 Ga, formed from the intense regional metamorphism of sandstone, leading to the recrystallization and interlocking of quartz grains.
