mineral

Milky Quartz with Iron Staining

Quartz (Silicon Dioxide, SiO2)

Hardness: 7 on the Mohs scale. Color: White/milky with reddish-brown oxidation. Luster: Vitreous to greasy. Crystal Structure: Hexagonal (trigonal). Cleavage: None (conchoidal fracture). Specific Gravity: 2.65.

Hardness: 7 on the Mohs scale
Color: White/milky with reddish-brown oxidation
Luster: Vitreous to greasy

Identified March 7, 2026More mineral →

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Physical properties

Formation & geological history

Formed from silica-rich hydrothermal solutions or cooling magma in veins. Milky appearance is caused by microscopic inclusions of fluids or gas trapped during crystal growth. Iron staining occurs later via weathering.

Uses & applications

Source of silicon for semiconductors and glass. Often used as decorative gravel, in landscaping, or as a common specimen for beginner rock collectors.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. The 'milky' look is actually a result of millions of tiny bubbles of liquid or gas trapped inside as the crystal grew.

Field identification & locations

Identify in the field by its ability to scratch glass and its lack of cleavage. Look for it in quartz veins or as float in soil. It is very common in metamorphic and igneous terrains globally.

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