mineral

Milky Quartz with Iron Staining

Quartz (Silicon Dioxide, SiO2)

Hardness: 7 on the Mohs scale. Color: Opaque white to translucent with yellowish-brown iron oxide streaks. Luster: Vitreous to greasy. Crystal structure: Trigonal/Hexagonal. Cleavage: None (conchoidal fracture). Specific gravity: 2.65.

Hardness: 7 on the Mohs scale
Luster: Vitreous to greasy

Identified March 29, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the cooling of silica-rich magma or from hydrothermal veins. The milky appearance is caused by microscopic fluid inclusions trapped during crystal growth. Iron staining occurs later due to weathering and groundwater exposure.

Uses & applications

Used in the production of glass, ceramics, and sandpaper. Also used in construction as an aggregate and in jewelry as a semi-precious gemstone (cabochons or tumbled stones). High-purity quartz is used in electronics and clocks.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Milky quartz can sometimes contain microscopic traces of gold in hydrothermal veins, a phenomenon highly sought after by prospectors.

Field identification & locations

Identify in the field by its ability to scratch glass, its lack of cleavage (it breaks in curved, shell-like patterns), and its distinctive 'milky' opacity. Commonly found in riverbeds, mountain ranges, and gravel deposits worldwide.

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