mineral

Quartz (Milky/River Quartz)

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Milky white with iron-staining (yellow/brown); Luster: Vitreous to waxy; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 on Mohs scale
Color: Milky white with iron-staining (yellow/brown)
Luster: Vitreous to waxy

Identified March 18, 2026More mineral →

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Physical properties

Formation & geological history

Formed through hydrothermal processes, crystallization from magma, or as a byproduct of metamorphic activity. This specific specimen appears to be a river stone, meaning it has been mechanically weathered and rounded by water transport over centuries to millennia.

Uses & applications

Used widely in glassmaking, electronics (piezoelectric properties), abrasives, and as construction aggregate. While this specific tumbled specimen is common, high-purity quartz is essential for industrial silicon production.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Ancient Greeks believed clear quartz was deeply frozen ice that would never melt. The milky appearance is caused by tiny fluid inclusions of gas or liquid trapped during the crystal's growth.

Field identification & locations

Identify in the field by its inability to be scratched by a steel knife, its irregular fracture, and lack of visible cleavage planes. It is commonly found in stream beds, beaches, and eroded mountain outcrops globally.