mineral

Milky Quartz Pebble

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale), Color: Translucent white to milky white, Luster: Vitreous to waxy, Crystal Structure: Trigonal/Hexagonal, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65

Identified June 19, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale), Color: Translucent white to milky white, Luster: Vitreous to waxy, Crystal Structure: Trigonal/Hexagonal, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65

Formation & geological history

Quartz forms in a wide variety of environments, most commonly from the cooling of magma (igneous) or hydrothermally in veins. This specific specimen is a water-worn river pebble, likely eroded from a vein and tumbled over centuries in a stream or beach environment.

Uses & applications

Used in glassmaking, electronics (piezoelectric properties), abrasives, and as decorative gravel or landscape stone. Tumbled specimens are popular in beginner rock collections.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. The 'milky' appearance is caused by tiny inclusions of gas or liquid trapped during crystal growth.

Field identification & locations

Identify in the field by its hardness (it will scratch glass) and lack of cleavage. It is found globally in riverbeds, beaches, and mountain trails. Collectors should look for smoothness and translucency.