mineral

Quartz (Milky/Common)

Silicon Dioxide (SiO2)

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

Hardness: 7 on Mohs scale
Color: White to translucent
Luster: Vitreous (glassy) to greasy

Identified March 23, 2026More mineral →

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Physical properties

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

Formation & geological history

Forms in a wide variety of environments including igneous (granite/pegmatite), metamorphic (quartzite), and sedimentary contexts. It precipitates from hydrothermal fluids or crystallizes from cooling magma. Quartz is found across all geological ages from the Archaean to the present.

Uses & applications

Used widely in glassmaking, electronics (piezoelectric properties), abrasives, construction aggregate, and as a semi-precious gemstone in jewelry (when found in clear or colored varieties).

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Ancient Greeks named it 'krustallos' meaning 'icy cold,' believing it was permanently frozen ice because it was found near glaciers.

Field identification & locations

Identify in the field by its ability to scratch glass (Hardness 7), Lack of cleavage, and its conchoidal (shell-like) fracture. Found globally in riverbeds, mountains, and beaches. It is the primary component of most sand.