sedimentary

Weathered brown sandstone or quartzite cobble

Indeterminate sandstone; possibly quartz-rich quartzite

AI-generated identification · may be incorrect

Brown, reddish, and cream mottling with a dull to slightly granular luster; likely quartz-rich. Hardness about 5–7 Mohs, no obvious cleavage, and massive texture; exact identification requires a fresh surface and acid/hardness tests.

Identified August 16, 2026More sedimentary →

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Physical properties

Formation & geological history

If sandstone, it formed from cemented sand grains in an ancient river, beach, dune, or shallow-marine environment, commonly ranging from Paleozoic to Mesozoic in age. If quartzite, burial and metamorphism recrystallized the sandstone during mountain building.

Uses & applications

Common sandstone is used for building stone, paving, and aggregate; quartzite is used for durable construction stone, countertops, and decorative landscaping. This individual cobble has minimal commercial value.

Geological facts

The rounded shape indicates transport by water, waves, or glacial action. Its mixed brown coloration likely reflects iron-oxide staining and weathering.

Field identification & locations

Look for visible sand grains and grains that scratch glass for sandstone; quartzite has interlocking quartz grains and usually breaks across grains rather than around them. Common in riverbeds, beaches, glacial deposits, and sandstone terrains.