mineral
Gray chalcedony or quartz fragment
Microcrystalline quartz, SiO₂ (tentative)
AI-generated identification · may be incorrectSmall irregular gray, translucent-to-opaque fragment with a waxy to dull luster and possible conchoidal fracture. Quartz has Mohs hardness 7, no cleavage, and specific gravity about 2.65; the image is insufficient to confirm exact variety.
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Physical properties
Small irregular gray, translucent-to-opaque fragment with a waxy to dull luster and possible conchoidal fracture. Quartz has Mohs hardness 7, no cleavage, and specific gravity about 2.65; the image is insufficient to confirm exact variety.
Formation & geological history
Likely silica deposited from groundwater or volcanic fluids, potentially forming chalcedony in cavities or veins; age cannot be determined visually. It may also be a broken piece of quartz-rich rock or manufactured glass, though its appearance is more consistent with a natural mineral.
Uses & applications
Quartz and chalcedony are used for abrasives, countertops, tools, carvings, and occasional jewelry; this small fragment has negligible commercial value.
Geological facts
Gray chalcedony commonly owes its color to microscopic inclusions or structural defects. A steel nail should not scratch it, while quartz should scratch ordinary glass.
Field identification & locations
Commonly found in volcanic cavities, sedimentary veins, gravel, and weathered quartz deposits worldwide. Confirm with a hardness test, glass-scratch test, conchoidal fracture, and ideally a loupe or streak test; avoid testing valuable specimens.
