mineral

Milky quartz with iron-oxide staining

Quartz, silicon dioxide (SiO₂), cryptocrystalline-to-coarse crystalline aggregate

AI-generated identification · may be incorrect

White to translucent, vitreous-to-waxy luster, irregular fracture, no obvious cleavage; Mohs hardness 7 and specific gravity about 2.65. The yellow-orange coating is likely limonite/goethite staining or a thin iron-rich host-rock rind.

Identified September 21, 2026More mineral →

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Physical properties

Formation & geological history

Quartz precipitated from silica-rich hydrothermal fluids or formed in a quartz vein, with later weathering producing iron staining. Its exact geological age cannot be determined from the photograph; such specimens occur in rocks of many ages.

Uses & applications

Common quartz is used in glass, ceramics, abrasives, engineered stone, and electronics; attractive pieces are sold as display specimens or lapidary material. This example has modest decorative value.

Geological facts

Milky appearance results from microscopic fluid inclusions, fractures, or impurities scattering light. Quartz is among the most abundant minerals in Earth’s continental crust.

Field identification & locations

Identify by its glassy appearance, hardness, lack of cleavage, and inability to scratch it with a steel knife; the yellow rind suggests weathered iron minerals. Common worldwide in veins, geodes, and granitic or metamorphic terrains.