mineral

Tumbled milky quartz (likely quartz with a dark mineral inclusion)

Quartz, silicon dioxide (SiO₂), with an unidentified dark inclusion

AI-generated identification · may be incorrect

Hardness 7 Mohs; white to translucent, vitreous-to-waxy luster, no cleavage, conchoidal fracture, and hexagonal crystal structure before tumbling. The dark patch may be biotite, tourmaline, iron/manganese oxide, or another included mineral.

Identified August 30, 2026More mineral →

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Physical properties

Formation & geological history

Quartz crystallizes from silica-rich igneous, hydrothermal, and metamorphic fluids; inclusions formed during or after crystal growth. The specimen has been mechanically polished and its geological age cannot be determined from the image.

Uses & applications

Used as a decorative tumbled stone, lapidary material, and inexpensive jewelry or craft component; quartz is also important industrially in glass, electronics, and abrasives.

Geological facts

Quartz is one of Earth’s most abundant minerals and is the defining component of many veins and quartz-rich rocks. Tumbled pieces commonly preserve internal inclusions that help distinguish them from plain glass.

Field identification & locations

Identify by its glassy appearance, lack of cleavage, hardness, and inability to scratch it with a steel knife; a reliable diagnosis requires testing the dark inclusion. Common sources include Brazil, Madagascar, India, and the United States.