mineral
Tumbled milky quartz (likely quartzite or chalcedony)
Quartz, SiO₂; possibly microcrystalline chalcedony
AI-generated identification · may be incorrectWhite to cream, translucent, with a vitreous-to-waxy luster and a visible healed/fracture seam. Quartz has Mohs hardness 7, hexagonal crystal structure, no cleavage, conchoidal fracture, and specific gravity about 2.65; the rounded shape is human-tumbled.
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Physical properties
White to cream, translucent, with a vitreous-to-waxy luster and a visible healed/fracture seam. Quartz has Mohs hardness 7, hexagonal crystal structure, no cleavage, conchoidal fracture, and specific gravity about 2.65; the rounded shape is human-tumbled.
Formation & geological history
Quartz formed from silica-rich fluids or cooling igneous rocks; quartzite forms when sandstone is metamorphosed, while chalcedony precipitates in cavities. The specimen’s geological age cannot be determined from the photograph.
Uses & applications
Used as a decorative stone, lapidary material, countertop aggregate, and inexpensive jewelry or meditation stone. Common tumbled pieces generally have modest value.
Geological facts
The cloudy appearance results from microscopic fluid inclusions, fractures, or fine-grained quartz. The central line may be a natural healed fracture, and a polished surface can obscure diagnostic crystal faces.
Field identification & locations
Common in quartz-rich gravels, veins, pegmatites, and metamorphic terrains worldwide; major sources include Brazil, Madagascar, the United States, and India. A glass-scratching test can support quartz identification, but avoid damaging the polished specimen.
