Quartz

Physical Properties

Hardness: 7 on Mohs scale; Color: White to colorless (milky quartz); Luster: Vitreous to greasy; Crystal Structure: Hexagonal (trigonal); Cleavage: Indistinct/Conchoidal fracture; Specific Gravity: 2.65.

Formation & Geological History

Forms in a wide variety of environments, most commonly from cooling igneous magmas or hydrothermal veins. It is found in crustal rocks of all ages and is extremely resistant to weathering.

Uses & Applications

Used extensively in glass making, electronics (piezoelectric properties), abrasives, as a flux in metallurgy, and as a gemstone/ornamental stone.

Geological Facts

Quartz is the second most abundant mineral in Earth's continental crust. Pure quartz is known as rock crystal, while Milky Quartz (shown) gets its appearance from tiny fluid inclusions of gas or liquid.

Field Identification & Locations

Identify in the field by its hardness (will scratch glass/steel), conchoidal fracture (curved glass-like breaks), and lack of cleavage. Very common in granitic mountains and riverbeds.

Identified on: 4/29/2026

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