Rock Identifier
Milky quartz (Quartz (silicon dioxide, SiO₂)) — mineral
mineral

Milky quartz

Quartz (silicon dioxide, SiO₂)

AI-generated identification · may be incorrect

White to translucent, vitreous-to-waxy luster with irregular fracture; Mohs hardness 7, no cleavage, hexagonal crystal structure, and specific gravity about 2.65. The rough surface and shape suggest a broken fragment rather than a polished specimen.

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Physical properties

White to translucent, vitreous-to-waxy luster with irregular fracture; Mohs hardness 7, no cleavage, hexagonal crystal structure, and specific gravity about 2.65. The rough surface and shape suggest a broken fragment rather than a polished specimen.

Formation & geological history

Forms when silica-rich fluids crystallize in veins, cavities, and igneous or metamorphic rocks; its age depends on the host deposit, commonly ranging from millions to billions of years. The cloudy appearance results from microscopic fluid inclusions or structural defects.

Uses & applications

Used as an industrial silica source, in glass and ceramics, abrasives, countertops, and occasionally ornamental carvings; attractive specimens are collected but usually have modest value.

Geological facts

Quartz is one of Earth’s most abundant minerals and is piezoelectric, generating an electrical charge under pressure. Milky quartz is generally less transparent and less valuable than clear or colored quartz varieties.

Field identification & locations

Identify it by its glassy appearance, white translucency, hardness sufficient to scratch ordinary glass, and lack of cleavage; common localities include Brazil, Madagascar, the United States, and alpine regions. Avoid acid testing, which does not meaningfully distinguish quartz.