
sedimentary
Quartz-rich sandstone (possibly arkosic sandstone)
Clastic sandstone composed mainly of quartz (SiO₂), with feldspar and mica fragments cemented by silica or carbonate
AI-generated identification · may be incorrectTypically Mohs 6–7; pale tan to gray, granular, and vitreous to dull. Visible sand-sized grains and uneven porous texture are characteristic; individual grains may sparkle from quartz or mica.
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Physical properties
Typically Mohs 6–7; pale tan to gray, granular, and vitreous to dull. Visible sand-sized grains and uneven porous texture are characteristic; individual grains may sparkle from quartz or mica.
Formation & geological history
Formed when sand accumulated, compacted, and cemented in a river, beach, dune, or shallow-marine environment. Its exact geological age cannot be determined from the photograph; sandstone ranges from Precambrian to recent.
Uses & applications
Used as building stone, paving, aggregate, and decorative material; attractive pieces are collected as specimens. It has little jewelry value unless unusually colorful or cemented with gem minerals.
Geological facts
The specimen appears unusually coarse and porous, possibly a weathered or weakly cemented sandstone, rather than a crystalline igneous rock. A hand lens can reveal rounded versus angular grains and distinguish quartz from flaky mica.
Field identification & locations
Common worldwide, especially in sedimentary basins and former beaches or river systems. Confirm identification by checking for gritty grains, lack of interlocking crystals, and possible fizz with dilute hydrochloric acid if carbonate cement is suspected.
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