mineral

Quartz (Milky/Common)

Quartz (Silicon Dioxide, SiO2)

Hardness: 7 on Mohs scale; Color: Milky white to tan; Luster: Vitreous (glassy) to greasy; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 on Mohs scale
Color: Milky white to tan
Luster: Vitreous (glassy) to greasy

Identified March 16, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Milky white to tan; Luster: Vitreous (glassy) to greasy; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Formation & geological history

Formed through the cooling of silica-rich magma or from hydrothermal veins. It is found in all geological environments (igneous, metamorphic, and sedimentary) and across all geological ages from the Precambrian to the Present.

Uses & applications

Used widely in glassmaking, abrasives, foundry sand, and as a component in concrete. High-purity quartz is used in electronics and watches (piezoelectric properties). Specimens like these are common for amateur collecting and tumbling.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Ancient Greeks believed quartz was actually ice that had frozen so hard it would never melt, which is why they called it 'krystallos'.

Field identification & locations

Identify in the field by its hardness (it will scratch glass and steel), lack of cleavage, and translucent 'milky' appearance. It is found globally, often as pebbles in riverbeds or as veins in larger rock outcrops.

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