mineral

Quartz (Milky Quartz pebble)

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: White/opaque (milky); Luster: Vitreous to greasy; Crystal Structure: Trigonal (hexagonal system); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Color: White/opaque (milky)
Luster: Vitreous to greasy

Identified March 8, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: White/opaque (milky); Luster: Vitreous to greasy; Crystal Structure: Trigonal (hexagonal system); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Formation & geological history

Formed through the crystallization of magma or hydrothermal activity in veins. This specific specimen appears to be water-worn, indicating a sedimentary transport environment like a riverbed or beach. Geological age can range from Precambrian to recent.

Uses & applications

Used in glassmaking, ceramics, electronics (due to piezoelectric properties), and as an abrasive. While common milky quartz is rarely used in high-end jewelry, it is used for beads and decorative landscaping stones.

Geological facts

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

Field identification & locations

Identify in the field by its inability to be scratched by a steel knife (hardness 7), lack of cleavage, and white opaque color. Found globally in almost all geological environments, particularly mountain streams and coastal areas.