mineral

Quartz (River Pebble)

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Tan, milky white, or yellowish; Luster: Vitreous to waxy; Crystal structure: Trigonal/Hexagonal (though massive/rounded here); Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 on Mohs scale
Color: Tan, milky white, or yellowish
Luster: Vitreous to waxy

Identified April 7, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the cooling of magma or precipitation from hydrothermal veins. This specific specimen is a water-worn river pebble, likely weathered out of a larger host rock and smoothed over thousands of years by fluvial action.

Uses & applications

Used in glassmaking, electronics (piezoelectric properties), abrasives, and as a common decorative landscape stone. Tumbled stones are used in jewelry and crystal collecting.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. It is highly resistant to chemical and physical weathering, which is why it often survives as rounded pebbles long after other minerals have decomposed.

Field identification & locations

Identify in the field by its hardness (it will easily scratch glass) and lack of cleavage. It is commonly found in riverbeds, beaches, and gravel pits worldwide. For collectors, look for clarity or unique inclusions.