mineral
Milky quartz (rough quartz fragment)
Quartz, silicon dioxide (SiO₂)
AI-generated identification · may be incorrectTypically white to translucent with a glassy-to-waxy luster; Mohs hardness 7, no cleavage, conchoidal fracture, and trigonal crystal structure. The irregular, cloudy appearance is consistent with milky quartz, though the photograph alone cannot exclude pale calcite or glass.
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Physical properties
Typically white to translucent with a glassy-to-waxy luster; Mohs hardness 7, no cleavage, conchoidal fracture, and trigonal crystal structure. The irregular, cloudy appearance is consistent with milky quartz, though the photograph alone cannot exclude pale calcite or glass.
Formation & geological history
Forms in hydrothermal veins, pegmatites, and silica-rich igneous rocks when quartz crystallizes from hot fluids or cooling magma. Quartz is common from Precambrian to modern geological settings.
Uses & applications
Used for glass, ceramics, abrasives, engineered stone, and electronics; attractive pieces are sold as inexpensive mineral specimens. It is generally not gem quality.
Geological facts
The cloudy color results from microscopic fluid inclusions, fractures, or mineral impurities. Quartz can scratch ordinary steel and glass, helping distinguish it from calcite and man-made glass.
Field identification & locations
Common worldwide, including Brazil, Madagascar, the United States, and alpine regions; identify by hardness, lack of cleavage, and conchoidal fracture. A hardness or acid test should be done only on an inconspicuous area.
