metamorphic
Tumbled quartz-rich pebble, possibly chert or quartzite
Quartz (SiO₂), likely in a fine-grained quartzite or silicified rock matrix
AI-generated identification · may be incorrectHardness about 7 Mohs; tan-brown, opaque to slightly translucent, with a dull to waxy luster and irregular fracture. The rounded shape suggests natural abrasion or tumbling; crystal structure is microcrystalline and cleavage is absent.
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Physical properties
Hardness about 7 Mohs; tan-brown, opaque to slightly translucent, with a dull to waxy luster and irregular fracture. The rounded shape suggests natural abrasion or tumbling; crystal structure is microcrystalline and cleavage is absent.
Formation & geological history
Likely formed by silica-rich sediment cementation and/or metamorphic recrystallization, followed by erosion and rounding. Exact geological age and identity cannot be determined from the photograph alone.
Uses & applications
Small specimens are mainly used for collecting, crafts, and educational displays; quartz-rich stone is also used as aggregate and industrial silica when abundant.
Geological facts
The dark markings may be iron-oxide staining, inclusions, or surface fractures. It could also be a weathered jasper or chert rather than quartzite.
Field identification & locations
Test with a steel file or glass: genuine quartz-rich material should resist scratching glass; a streak test, translucency check, and close examination of grain texture would improve identification. Common worldwide, especially in river gravels and weathered silica-rich terrains.
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