igneous
Weathered quartz-rich pebble
Likely quartzite or quartz-rich sandstone; exact identification is uncertain from the photograph
AI-generated identification · may be incorrectTan-brown, rounded, fine-grained stone with dull to weakly glassy luster and dark weathering spots. Likely hardness about 6–7 Mohs; quartz grains have no cleavage, but the specimen’s grain size and structure are not clear.
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Physical properties
Tan-brown, rounded, fine-grained stone with dull to weakly glassy luster and dark weathering spots. Likely hardness about 6–7 Mohs; quartz grains have no cleavage, but the specimen’s grain size and structure are not clear.
Formation & geological history
Probably derived from erosion of a quartz-rich sandstone or metamorphic quartzite, later rounded by stream or beach transport. Its geological age cannot be determined visually and depends on the source formation.
Uses & applications
As an ordinary pebble it has little commercial use; quartzite is used as aggregate, building stone, and occasionally decorative material. This individual specimen has minimal market value unless locality or unusual composition is documented.
Geological facts
The rounded shape indicates substantial transport and abrasion. A porcelain-streak test, acid test, and close examination of grain boundaries would help distinguish quartzite from sandstone or other tan rocks.
Field identification & locations
Common in streambeds, beaches, glacial deposits, and weathered gravel, especially where quartz-rich bedrock occurs. Test hardness against glass and inspect a fresh chip: interlocking quartz grains suggest quartzite, while visible cemented sand grains suggest sandstone.
