mineral

Quartz (River Pebble)

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Milky white to translucent tan; Luster: Vitreous (glassy) when wet or polished, waxy when worn; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 on Mohs scale
Color: Milky white to translucent tan
Luster: Vitreous (glassy) when wet or polished, waxy when worn

Identified March 26, 2026More mineral →

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Physical properties

Formation & geological history

Formed from silica-rich hydrothermal veins or within igneous and metamorphic rocks. This specific specimen has been rounded and smoothed through alluvial processes (water erosion) in a river or beach environment over thousands of years.

Uses & applications

Common industrial use includes glass making and abrasives. As a pebble, it is used in landscaping, aquarium decor, and primitive stone tools. High-quality varieties are used in jewelry as semi-precious gemstones.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Because of its high hardness and chemical stability, it often outlasts other minerals in a rock, leading to the formation of quartz-rich sand and river pebbles.

Field identification & locations

Identify in the field by its inability to be scratched by a steel knife and its lack of cleavage. It is commonly found in riverbeds, glacial tills, and beaches worldwide. Collectors often look for clarity or unique inclusions within the stone.