mineral

Quartz (Milky/Yellowish variety)

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Milky white to translucent with yellowish iron staining; Luster: Vitreous (glassy) to greasy; Crystal structure: Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 on Mohs scale
Color: Milky white to translucent with yellowish iron staining
Luster: Vitreous (glassy) to greasy

Identified April 7, 2026More mineral →

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Physical properties

Formation & geological history

Formed from silica-rich hydrothermal fluids cooling in rock cavities or veins. This specific specimen appears to be a water-worn river cobble or pebble. It can be found in almost all geological ages and environments.

Uses & applications

Used in glassmaking, abrasives, electronics (piezoelectric properties), and as decorative stones or carving materials.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Pure quartz is clear, but tiny fluid inclusions cause the 'milky' white appearance seen here, and iron oxides often cause the yellow tint.

Field identification & locations

Identify by its inability to be scratched by a steel knife (hardness 7) and its lack of cleavage. It is ubiquitous in riverbeds and mountainous terrain worldwide.

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