mineral
Tumbled jasper or altered chalcedony
Microcrystalline quartz (SiO₂), possibly jasper/chalcedony
AI-generated identification · may be incorrectOpaque to slightly translucent gray-green, cream, and brown material with a dull-to-waxy luster and irregular internal patterning. Quartz hardness is about 7 Mohs; no visible cleavage, and specific gravity is approximately 2.6.
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Physical properties
Opaque to slightly translucent gray-green, cream, and brown material with a dull-to-waxy luster and irregular internal patterning. Quartz hardness is about 7 Mohs; no visible cleavage, and specific gravity is approximately 2.6.
Formation & geological history
Likely silica-rich material formed when groundwater deposited microcrystalline quartz in cavities or replaced volcanic or sedimentary rock; the specimen appears naturally worn or lightly polished. Exact age and locality cannot be determined from the photograph.
Uses & applications
Commonly used for cabochons, beads, carvings, and inexpensive ornamental stones; rough pieces are mainly collector specimens. Typical value is low unless pattern, color, or locality is exceptional.
Geological facts
Jasper is opaque and commonly colored by iron or other impurities, while chalcedony is generally more translucent; many specimens grade between the two. The image alone cannot reliably distinguish this from several altered silicate rocks.
Field identification & locations
Field identification requires a scratch test: quartz should scratch ordinary glass, while a steel knife should not scratch it; inspect for waxy luster and conchoidal fracture. Similar-looking serpentine, nephrite, or weathered rock would require hardness, streak, and locality tests.
