mineral

Milky quartz (quartz crystal fragment)

Quartz, silicon dioxide (SiO₂)

AI-generated identification · may be incorrect

Hardness 7 Mohs; translucent white to colorless, vitreous luster, and hexagonal crystal structure. It has indistinct cleavage and conchoidal fracture; the pictured piece appears naturally fractured or roughly cleaved.

Identified September 15, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich fluids crystallize in cavities, veins, and igneous or metamorphic rocks; specimens may range from Precambrian to recent hydrothermal deposits. Commonly occurs with feldspar, mica, and metallic sulfides.

Uses & applications

Used extensively in glass, ceramics, electronics, abrasives, foundry work, and engineered stone; attractive pieces are sold as inexpensive mineral specimens and occasionally cut as gemstones.

Geological facts

Quartz is among Earth’s most abundant minerals and is piezoelectric, generating an electrical charge under mechanical stress. Milky appearance results from microscopic fluid inclusions, fractures, or mineral impurities.

Field identification & locations

Identify by its glassy luster, lack of cleavage, conchoidal fracture, and inability to scratch it with a steel knife; it should scratch ordinary window glass. Common localities include Brazil, Madagascar, the United States, and worldwide quartz veins.