mineral

Quartz (River Cobble)

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Milky white to tan; Luster: Vitreous to waxy (when weathered); Crystal structure: Trigonal/Hexagonal; Cleavage: None/Conchoidal fracture.

Hardness: 7 on Mohs scale
Color: Milky white to tan
Luster: Vitreous to waxy (when weathered)

Identified July 19, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Milky white to tan; Luster: Vitreous to waxy (when weathered); Crystal structure: Trigonal/Hexagonal; Cleavage: None/Conchoidal fracture.

Formation & geological history

Formed from hydrothermal veins or within igneous and metamorphic rocks. This specific specimen shows signs of mechanical weathering and rounding by water transport, likely in a river or glacial environment.

Uses & applications

Crushed for construction aggregate, used in glassmaking, and collected as decorative river rocks or garden landscaping stones.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Its high hardness and lack of cleavage make it extremely resistant to chemical and physical weathering, which is why it is so common in riverbeds.

Field identification & locations

Identify by its ability to scratch glass and its lack of obvious cleavage planes. Found globally in almost every geological setting, especially riverbanks and beaches.