mineral

Milky Quartz with Iron Staining

Silicon Dioxide (SiO2)

Hardness: 7 on the Mohs scale. Color: Opaque white to creamy tan/orange due to iron oxide staining. Luster: Vitreous to greasy. Crystal Structure: Hexagonal (Trigonal). Cleavage: None (conchoidal fracture). Specific Gravity: 2.65.

Hardness: 7 on the Mohs scale
Color: Opaque white to creamy tan/orange due to iron oxide staining
Luster: Vitreous to greasy

Identified March 8, 2026More mineral →

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Physical properties

Formation & geological history

Formed from silica-rich hydrothermal solutions cooling within veins or as a result of regional metamorphism. The iron staining occurs through weathering and oxidation (rusting) of nearby iron-bearing minerals like pyrite or hematite over thousands of years.

Uses & applications

Used industrially as an abrasive, in the production of glass and ceramics, and as a source of silicon for electronics. Lower-grade specimens are often used in landscaping or as gravel.

Geological facts

Quartz is the most abundant and diverse mineral on Earth's continental crust. 'Milky' quartz gets its opacity from microscopic inclusions of gas and liquid that were trapped during the crystal's growth.

Field identification & locations

Identify it in the field by its inability to be scratched by a steel knife (hardness 7) and its lack of cleavage. It is found globally in almost all geological environments, often as a primary component of granite or as distinct veins in metamorphic rock.

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