mineral

Milky Quartz (polished heart)

Quartz (Silicon Dioxide, SiO2)

Hardness: 7 on Mohs scale; Color: Milky white to pale yellow; Luster: Vitreous/Waxy when polished; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 on Mohs scale
Color: Milky white to pale yellow
Luster: Vitreous/Waxy when polished

Identified March 18, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Milky white to pale yellow; Luster: Vitreous/Waxy when polished; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Formation & geological history

Formed through the crystallization of silica-rich hydrothermal solutions or cooling magma. Its characteristic white cloudiness is caused by minute fluid inclusions of gas and/or liquid trapped during crystal growth.

Uses & applications

Commonly used in lapidary work for cabochons, carvings, and tumbled stones. In industry, quartz is used in glassmaking, electronics (piezoelectric properties), and as an abrasive.

Geological facts

Milky quartz is the most common variety of crystalline quartz. While it lacks the transparency of clear rock crystal, its inclusions represent 'geological fossils' of the fluids present during its formation.

Field identification & locations

Identify by its hardness (will scratch glass), waxy luster, and lack of cleavage. It is ubiquitous in continental crust and found in nearly all geological environments worldwide. Collectors should look for even color and a lack of surface fractures.

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