mineral

Quartz (Milky or Smoky Quartz variety)

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale. Color: Translucent white to light gray. Luster: Vitreous (glassy) to greasy. Crystal Structure: Hexagonal (trigonal). Cleavage: None (conchoidal fracture). Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Translucent white to light gray
Luster: Vitreous (glassy) to greasy

Identified July 15, 2026More mineral →

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Physical properties

Formation & geological history

Formed from cooling magma in igneous rocks or through hydrothermal activity where silica-rich fluids precipitate into veins and cavities. This specific specimen appears to be a water-worn river cobble.

Uses & applications

Used extensively in glassmaking, electronics (piezoelectric properties), abrasives, construction aggregates, and as gemstones or decorative landscaping stones.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. It is chemically very stable and resistant to weathering, which is why it often remains as rounded pebbles in riverbeds long after other minerals have weathered away.

Field identification & locations

Identify in the field by its hardness (will scratch glass and steel), lack of cleavage, and characteristic glassy fracture edges. Common in riverbeds, gravel pits, and mountainous regions worldwide.

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Arenite (SiO2 based)

sedimentary

Sandstone with Mineral Veining or Crust

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Schist

Metamorphic

Potassium Feldspar (Orthoclase)

Orthoclase (KAlSi3O8)

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Gypsum (variety Selenite or Alabaster)

Calcium sulfate dihydrate (CaSO4·2H2O)

Mineral

Epidote

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