mineral

Milky Quartz Pebble

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Opaque white to translucent; Luster: Vitreous to greasy; Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Color: Opaque white to translucent
Luster: Vitreous to greasy

Identified March 21, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Opaque white to translucent; Luster: Vitreous to greasy; Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Formed from the cooling of silica-rich hydrothermal fluids in veins or pegmatites; the white 'milky' color is caused by microscopic fluid inclusions trapped during crystal growth. This specimen has been rounded by fluvial (river) or glacial transport.

Uses & applications

Common quartz is used for abrasive blasting, glass making, and as a source of silicon for electronics. Rounded pebbles are popular for landscaping, decorative aquariums, and rock tumbling.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Milky quartz is the most common variety of quartz. Its white color is often likened to ice or frozen milk, leading to many cultural myths regarding its origins as 'unmeltable ice'.

Field identification & locations

Identify in the field by its ability to scratch glass, its lack of cleavage (it breaks in curved surfaces like glass), and its distinctive white color. It is ubiquitously found in river beds, beaches, and glacial till worldwide.