sedimentary

Quartz Pebble

Crystalline Silica (SiO2)

Hardness: 7 (Mohs scale); Color: semi-transparent, milky white, gray; Luster: vitreous to waxy; Texture: water-worn, rounded. Clear areas show conchoidal fracture.

Hardness: 7 (Mohs scale)
Color: semi-transparent, milky white, gray
Luster: vitreous to waxy

Identified July 19, 2026More sedimentary →

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Physical properties

Hardness: 7 (Mohs scale); Color: semi-transparent, milky white, gray; Luster: vitreous to waxy; Texture: water-worn, rounded. Clear areas show conchoidal fracture.

Formation & geological history

Formed through the cooling of silica-rich magma or precipitation in hydrothermal veins. This specific specimen is a 'clast' that has been eroded from its parent rock and weathered/rounded in a high-energy environment like a river or beach.

Uses & applications

Primarily used as aggregate in construction, as a source of silica for glassmaking, or as decorative garden stone. Low-grade specimens are common landscape rocks.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Because of its high chemical and physical stability, it survives long-term erosion better than most other minerals, eventually becoming sand.

Field identification & locations

Identify by its ability to scratch glass and lack of reaction to acid. Commonly found in riverbeds, glacial deposits, and along coastlines worldwide. Look for the characteristic 'waxy' look when wet.