Milky Quartz
Image: James St. John (CC BY 2.0)
Mineral NameMilky Quartz
Chemical FormulaSiO2
Mohs Hardness7
Crystal Systemtrigonal
Lustervitreous
Streak Colorwhite
Cleavagenone (or very poor/indistinct)
Fractureconchoidal
Specific Gravity2.65
Colorswhite, off-white, translucent white
Transparencytranslucent
Type LocalityDiamond Hill, Ashaway Village, Hopkinton, Rhode Island, USA
Mineral GroupSilicates (Tectosilicates)
Usesindustrial (abrasives, ceramics), filler material, ornamental stone (less common for milky variety), collector
Associated Mineralsamethyst, feldspar, mica, calcite, pyrite
Raritycommon
Description
Milky quartz is a common variety of quartz characterized by its cloudy, opaque to translucent white appearance, often forming in massive aggregates or as vein fillings. The image shows milky quartz matrix with distinct purple amethyst crystals growing on it.
Geological Context
Milky quartz forms in a wide range of geological environments, including hydrothermal veins, pegmatites, and igneous and metamorphic rocks. Its milky appearance is often attributed to microscopic fluid inclusions trapped during crystal growth.
