mineral

Tumbled chalcedony or quartz

Microcrystalline silica, SiO₂ (likely chalcedony; possibly milky quartz)

AI-generated identification · may be incorrect

A small polished/tumbled, pale cream translucent stone with waxy-to-vitreous luster and conchoidal-looking surface fractures. Hardness is about 6.5–7 Mohs; cleavage is absent, and specific gravity is approximately 2.6. The dark spot may be an inclusion, cavity, or surface mark.

Identified August 18, 2026More mineral →

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Physical properties

Formation & geological history

Silica-rich groundwater deposited quartz fibers in cavities or fractures, commonly in volcanic rocks; the material may be Cenozoic or older depending on its source. Its rounded form is human-tumbled rather than naturally weathered.

Uses & applications

Used for inexpensive cabochons, beads, carvings, lapidary pieces, and ornamental objects; quartz and chalcedony are also used industrially for silica products.

Geological facts

Chalcedony is cryptocrystalline quartz, while milky quartz consists of larger interlocking crystals obscured by inclusions or fractures. Reliable separation requires magnification or testing.

Field identification & locations

Commonly found in volcanic terrains, gravels, and silica-rich veins worldwide, especially Brazil, Uruguay, India, Madagascar, and the western United States. A scratch test, refractive index, and inspection for fibrous texture can distinguish it from glass or plastic.