mineral

Quartz (Chert/Chalcedony Variety)

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale), Color: Translucent white to tan/pinkish, Luster: Vitreous to waxy, Crystal structure: Hexagonal (cryptocrystalline), Cleavage: None (Conchoidal fracture), Specific Gravity: 2.65

Identified February 6, 2026More mineral →

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Physical properties

Formation & geological history

Formed via chemical precipitation from silica-rich fluids in sedimentary environments or as a secondary mineral filling cavities in volcanic rocks. This specimen appears to be a cryptocrystalline variety common in many geological eras.

Uses & applications

Used industrially in glassmaking and abrasives. Historically used for stone tools (arrowheads). Lower-quality specimens are used in landscaping or construction aggregate.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Cryptocrystalline varieties like the one shown are often found as 'stream pebbles' because they are resistant to chemical weathering.

Field identification & locations

Identify in the field by its hardness (will scratch glass) and its curved, shell-like (conchoidal) fracture pattern. Commonly found in riverbeds, gravel pits, and desert pavements worldwide.

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