Quartz (Milky or Smoky variety)

Physical Properties

Hardness: 7 on Mohs scale; Color: Clear to white or smoky brown; Luster: Vitreous to greasy; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & Geological History

Quartz forms in a wide variety of environments, most commonly from the cooling of magma (igneous) or precipitation from hydrothermal veins. It is found in rocks ranging from the Archean era to the present day.

Uses & Applications

Used extensively in glassmaking, electronics (piezoelectric properties), abrasives, construction as an aggregate, and as semi-precious gemstones in jewelry.

Geological Facts

Quartz is the second most abundant mineral in Earth's continental crust. It is highly resistant to both chemical and physical weathering. Pure quartz is known as rock crystal.

Field Identification & Locations

Identify in the field by its hardness (it can scratch glass and steel), lack of cleavage, and characteristic glassy luster. Commonly found in granite outcroppings or as loose pebbles in stream beds.

Identified on: 5/12/2026

Mode: Standard