Milky Quartz

Physical Properties

Hardness: 7 on Mohs scale; Color: White to translucent gray; Luster: Vitreous to greasy; Crystal Structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & Geological History

Formed through the cooling and crystallization of silica-rich hydrothermal fluids or magma. This specific specimen appears to be a water-worn river cobble. It can originate from many geological eras, from Precambrian to recent.

Uses & Applications

Used as a gemstone (tumbled or carved), in glassmaking, as an abrasive, and in the production of silicon wafers for the electronics and solar industries.

Geological Facts

The 'milky' appearance is caused by tiny inclusions of gas or liquid trapped during the crystal's formation. It is the most common variety of crystalline quartz on Earth.

Field Identification & Locations

Identify in the field by its hardness (will scratch glass), lack of cleavage, and white color. It is extremely common in riverbeds, glacial deposits, and mountain ranges worldwide.

Identified on: 4/27/2026

Mode: Standard