mineral

Milky Quartz with Iron Staining

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale); Color: White to yellowish-orange; Luster: Vitreous to greasy; Crystal structure: Trigonal/Hexagonal; Cleavage: None/Conchoidal fracture; Specific gravity: 2.65

Hardness: 7 (Mohs scale)
Color: White to yellowish-orange
Luster: Vitreous to greasy

Identified July 7, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale); Color: White to yellowish-orange; Luster: Vitreous to greasy; Crystal structure: Trigonal/Hexagonal; Cleavage: None/Conchoidal fracture; Specific gravity: 2.65

Formation & geological history

Formed from silica-rich hydrothermal solutions in veins or as a component of igneous rocks. This specimen shows surface iron oxide staining (limonite/hematite) from weathering. Found in the Sierra Nevada foothills/Central Valley region, often associated with gold-bearing quartz veins.

Uses & applications

Construction aggregate, source of silica for glass and electronics, and often collected as a lapidary material or landscape stone.

Geological facts

Quartz is one of the most abundant minerals in the Earth's crust. The yellow staining is often called 'iron-stained quartz' and is a common indicator for prospectors looking for associated precious metals in the Mother Lode region of California.

Field identification & locations

Identify by its hardness (scratches glass), waxy to glassy luster, and lack of cleavage. This rounded pebble was likely found in a riverbed or alluvial deposit near Sacramento/Sierra foothills.

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