mineral

White chalcedony (possibly milky quartz) cabochon

Chalcedony, microcrystalline SiO₂; appearance may also represent milky quartz or synthetic imitation

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; white, translucent to opaque, waxy-to-glassy luster, cryptocrystalline quartz with no visible cleavage. The smooth oval cabochon is polished and likely dyed-free, though visual identification alone is inconclusive.

Identified September 8, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater deposits microcrystalline quartz in cavities and fractures, commonly in volcanic rocks; deposits range from Paleozoic to recent. This specimen has been cut and polished.

Uses & applications

Used for cabochon jewelry, beads, carvings, and ornamental objects; common-quality pieces have modest value.

Geological facts

Chalcedony is a quartz variety encompassing forms such as agate, jasper, and onyx. A conclusive identification requires testing because white glass, opalite, and ceramic imitations can look similar.

Field identification & locations

Common in Brazil, Uruguay, India, Madagascar, Turkey, and the western United States. Field clues include waxy luster, lack of cleavage, cool feel, and resistance to scratching by a steel knife; specific gravity is about 2.6.