mineral
Milky quartz (likely vein quartz)
Quartz, silicon dioxide (SiO₂)
AI-generated identification · may be incorrectTypically hardness 7 Mohs, white to translucent with a vitreous-to-waxy luster, poor/no cleavage, and conchoidal fracture; hexagonal crystal structure, though this specimen is massive and rounded. The cloudy appearance comes from microscopic fluid inclusions, fractures, or mineral impurities;…
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Physical properties
Typically hardness 7 Mohs, white to translucent with a vitreous-to-waxy luster, poor/no cleavage, and conchoidal fracture; hexagonal crystal structure, though this specimen is massive and rounded. The cloudy appearance comes from microscopic fluid inclusions, fractures, or mineral impurities; brown specks may be iron oxides or attached soil.
Formation & geological history
Forms when silica-rich hydrothermal fluids fill fractures and crystallize in veins, commonly during igneous or metamorphic activity; quartz is abundant from Precambrian rocks to the present. The rounded surface suggests natural weathering or transport, possibly with minor human smoothing.
Uses & applications
Used for glass, ceramics, abrasives, engineered stone, and silicon production; attractive translucent pieces are collected or used decoratively. It is generally not gem-grade because of cloudiness and inclusions.
Geological facts
Quartz is one of Earth’s most abundant minerals and is resistant to weathering, making it common in river gravels and residual soil. A steel knife should not scratch it, while quartz can scratch ordinary window glass.
Field identification & locations
Common in quartz veins, granite, pegmatites, metamorphic rocks, and stream deposits worldwide; major sources include Brazil, Madagascar, the United States, and Australia. Confirm with a hardness test and lack of cleavage, while avoiding tests on valuable or polished specimens.
