mineral

Milky Quartz with Iron Staining

Silicon Dioxide (SiO2)

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

Hardness: 7 on Mohs scale
Color: Cloudy white to pale yellow
Luster: Vitreous to greasy

Identified June 22, 2026More mineral →

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Physical properties

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

Formation & geological history

Forms through the crystallization of silica-rich hydrothermal fluids in veins or as a late-stage mineral in igneous pegmatites. The yellow tint is caused by surface deposits or inclusions of iron oxides (limonite).

Uses & applications

Used in glass making, as an abrasive, in electronics for its piezoelectric properties, and as a decorative stone or lapidary material.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Iron-stained quartz is often mistaken for citrine, but it is actually just quartz with a surface layer of rust.

Field identification & locations

Identify in the field by its hardness (will scratch glass), lacks cleavage, and often contains visible fractures. Commonly found in mountainous regions, riverbeds, and as veins in granite.

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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