mineral

Milky Quartz / Chalcedony

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Off-white, translucent grey with brownish-tan iron staining; Luster: Vitreous to waxy; Cleavage: None (conchoidal to uneven fracture); Specific Gravity: ~2.65

Hardness: 7 on Mohs scale
Color: Off-white, translucent grey with brownish-tan iron staining
Luster: Vitreous to waxy

Identified July 26, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Off-white, translucent grey with brownish-tan iron staining; Luster: Vitreous to waxy; Cleavage: None (conchoidal to uneven fracture); Specific Gravity: ~2.65

Formation & geological history

Forms primarily through hydrothermal activity, precipitation from silica-rich fluids in cavities, or crystallization in pegmatites and veins within various rock types.

Uses & applications

Used as decorative garden stones, raw material for lapidary work, landscaping, and as educational or rough mineral specimens for collectors.

Geological facts

Quartz is one of the most abundant minerals in the Earth's continental crust. Iron oxide surface staining frequently gives milky quartz and agate a tan or reddish hue.

Field identification & locations

Identified by its high hardness (scratches glass readily), conchoidal fracture, and lack of cleavage. Commonly found in stream beds, gravel deposits, pegmatites, and quartz veins worldwide.