mineral

Milky quartz with iron-oxide staining

Quartz, silicon dioxide (SiO₂), likely massive quartz; secondary iron oxides/hydroxides

AI-generated identification · may be incorrect

Typically hardness 7 Mohs, white to translucent with yellow-brown staining, vitreous to greasy luster, and no cleavage; conchoidal fracture and hexagonal crystal structure are characteristic, though this specimen appears massive and weathered.

Identified September 6, 2026More mineral →

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Physical properties

Formation & geological history

Quartz crystallized from silica-rich hydrothermal fluids or an igneous vein, with later oxidation staining from iron-bearing minerals. Its precise geological age and locality cannot be determined from the photograph.

Uses & applications

Common quartz is used in glass, ceramics, abrasives, engineered stone, and electronics; attractive pieces are sold as inexpensive mineral specimens or lapidary material.

Geological facts

The yellow-brown color is likely limonite/goethite coating or inclusions rather than the quartz itself. Quartz can scratch ordinary glass and steel but is not scratched by a steel knife.

Field identification & locations

Look for glassy luster, lack of cleavage, conchoidal fracture, and hardness near 7; acid testing is unnecessary. Common worldwide in veins, cavities, pegmatites, and hydrothermal deposits.