mineral

Milky quartz with iron-oxide staining

Quartz (SiO₂), massive or coarse-grained aggregate

AI-generated identification · may be incorrect

Typically Mohs hardness 7, white to translucent, vitreous-to-waxy luster, no cleavage, conchoidal fracture, and specific gravity about 2.65. The brown-red patches are likely limonite/goethite staining; darker grains may be minor mica or other matrix minerals.

Identified September 18, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich hydrothermal fluids fill fractures or crystallize in pegmatites and quartz veins. The specimen’s precise geological age cannot be determined from an image and depends on its host formation.

Uses & applications

Common quartz is used in glass, ceramics, engineered stone, abrasives, and electronics; attractive pieces are collected or used decoratively, though this specimen appears modestly gem-quality.

Geological facts

Its hardness should readily scratch ordinary glass, while a steel knife generally will not scratch clean quartz. Milky opacity results from microscopic fluid inclusions, fractures, or impurities.

Field identification & locations

Look for glassy luster, hardness, lack of cleavage, and conchoidal fracture; distinguish it from calcite, which is softer and cleaves readily. Quartz veins occur worldwide, especially in granites, metamorphic rocks, and hydrothermal districts.