mineral
Tumbled milky quartz (probable)
Quartz, silicon dioxide (SiO₂)
AI-generated identification · may be incorrectHardness 7 Mohs; white to translucent with pale tan inclusions, vitreous/waxy luster, and no visible cleavage. Crystalline quartz is trigonal, though tumbling has rounded and polished the specimen.
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Physical properties
Hardness 7 Mohs; white to translucent with pale tan inclusions, vitreous/waxy luster, and no visible cleavage. Crystalline quartz is trigonal, though tumbling has rounded and polished the specimen.
Formation & geological history
Likely formed in silica-rich veins or cavities as hydrothermal quartz; its exact geological age cannot be determined visually and may range from millions to billions of years. The rounded shape and glossy surface indicate human tumbling/polishing.
Uses & applications
Used as an inexpensive decorative stone, craft material, lapidary piece, and collector specimen; quartz is also important in glass, ceramics, electronics, and abrasives.
Geological facts
The tan internal areas may be iron-oxide staining or included feldspar/clay, making precise identification uncertain from the photograph alone. Quartz has no true cleavage and commonly breaks with a conchoidal fracture.
Field identification & locations
Common worldwide, including Brazil, Madagascar, the United States, and many vein deposits. Confirm with a scratch test against glass (quartz should scratch it) and inspect for a glassy fracture; avoid testing valuable polished pieces.
