mineral

Quartz Pebble

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale), Color: tan to milky white with iron staining, Luster: vitreous to waxy (weathered), Crystal structure: Trigonal (not visible in this water-worn specimen), Cleavage: None (conchoidal fracture)

Identified July 19, 2026More mineral →

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Physical properties

Formation & geological history

Formed in hydrothermal veins or igneous rocks like granite. This specific specimen has been chemically weathered and physically eroded, likely by water transport in a stream or riverbed.

Uses & applications

Used for architectural aggregate, aquarium decor, and as a source of silica for glass and electronics in bulk. Common specimens like this are primarily of educational or sentimental value.

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 weathering, which is why it often survives as pebbles long after other minerals have dissolved.

Field identification & locations

Identify by its ability to scratch glass and lack of reaction to acid. It is found globally in riverbeds, beaches, and soil. To collectors, these are 'pocket rocks' often kept for their smooth texture or interesting shapes.