mineral

Milky Quartz with Iron Staining

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Opaque white to tan with reddish-orange iron oxide staining; Luster: Vitreous to greasy; Crystal structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 on Mohs scale
Color: Opaque white to tan with reddish-orange iron oxide staining
Luster: Vitreous to greasy

Identified June 23, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the cooling of silica-rich hydrothermal fluids in veins or pegmatites. The white 'milky' appearance is caused by tiny fluid inclusions trapped during crystal growth. The reddish coloration is secondary limonite or hematite staining from weathering.

Uses & applications

Used widely in glassmaking, abrasives, and as a gemstone (druzy). It is also a significant ore of silicon for electronics and solar cells.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Milky quartz is often the variety found in large hydrothermal veins that can contain gold.

Field identification & locations

Identify by its hardness (it will easily scratch glass but cannot be scratched by a steel knife) and lack of cleavage planes. Commonly found in mountainous regions, riverbeds, and as vein material in various rock types.

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

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Nephrite Jade

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Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

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mineral