Quartz (Milky/Common Quartz)

Physical Properties

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

Formation & Geological History

Formed through crystallization of igneous magma or from hydrothermal veins. It is one of the most abundant minerals in Earth's crust and is found in all three types of rocks (igneous, sedimentary, and metamorphic).

Uses & Applications

Used in glassmaking, abrasives, silicon production for electronics, construction aggregate, and as a component in quartz countertops. Common specimens are also collected by hobbyists.

Geological Facts

Milky quartz gets its cloudy appearance from microscopic inclusions of fluids or gas trapped during the crystal's formation. It is the most common variety of crystalline quartz.

Field Identification & Locations

Identify in the field by its hardness (it will scratch glass and steel), lack of cleavage, and its characteristic vitreous luster. It is found globally in mountains, rivers, and beaches.

Identified on: 4/17/2026

Mode: Standard