sedimentary

Possible chert or weathered quartzite fragment

Microcrystalline quartz (SiO₂), identification uncertain from the photograph

AI-generated identification · may be incorrect

Brown, opaque, dull to weakly waxy luster, irregular conchoidal-looking fracture, and no visible crystal faces; quartz-rich material has Mohs hardness about 7 and typically scratches glass. Grain size and cleavage are not visible.

Identified August 16, 2026More sedimentary →

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Physical properties

Formation & geological history

If chert, it formed when silica-rich fluids replaced or cemented sediment, commonly during the Paleozoic–Cenozoic; if quartzite, it is metamorphosed sandstone of variable age. The fragment’s worn edges suggest natural weathering or human breakage.

Uses & applications

Common chert is used historically for tools and occasionally aggregate; quartzite is used as dimension stone, countertops, road aggregate, and decorative specimens. This small fragment has little commercial value.

Geological facts

Chert often occurs as nodules or beds in limestone and may show banding, fossils, or a sharp glassy fracture. Color can result from iron oxides, organic matter, or other impurities.

Field identification & locations

Test hardness against glass and a steel knife, inspect for a fine homogeneous texture, and use a streak test; definitive identification may require a fresh surface or microscopy. Common in sedimentary terrains worldwide.