mineral

Quartz-rich rock, possibly quartz vein or silicified breccia

Quartz (SiO₂), likely with iron-oxide/clay impurities

AI-generated identification · may be incorrect

Pale gray to tan, translucent edges, vitreous to dull luster, irregular fracture, and no obvious cleavage. Quartz hardness is Mohs 7; the rough, granular texture suggests fractured or intergrown quartz rather than a clean crystal.

Identified September 13, 2026More mineral →

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Physical properties

Formation & geological history

Likely formed when silica-rich hydrothermal fluids filled fractures, possibly brecciating and cementing older rock; iron staining and weathering produced the tan-brown areas. Exact age cannot be determined from the photograph.

Uses & applications

Common quartz-rich material is used for aggregate, silica, glass, and engineered stone; attractive pieces may be collected, but this specimen appears ordinary rather than gem quality.

Geological facts

The rounded outline may reflect natural weathering or human breakage. It is not possible to confirm whether the gray rim is quartz, host rock, or another mineral without testing.

Field identification & locations

At approximately 26.7°S, 53.6°W in southern Brazil, quartz veins and weathered crystalline rocks are geologically plausible. Test with a steel knife or glass: quartz should scratch glass and resist a knife; a streak test, acid test, and close examination of translucent grains would improve identification.