sedimentary

Weathered quartz-rich pebble

Quartz-rich sandstone or quartzite (identification uncertain from image)

AI-generated identification · may be incorrect

Light gray, rounded, fine-grained specimen with a dull to slightly sparkling surface and apparent layered or foliated edges. Likely dominated by quartz (Mohs 7), with possible feldspar, mica, or clay minerals; cleavage is absent to poor and specific gravity is roughly 2.6.

Identified August 15, 2026More sedimentary →

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Physical properties

Formation & geological history

If sandstone, it formed from cemented quartz sand; if quartzite, heat and pressure recrystallized sandstone during metamorphism. Its rounded shape indicates abrasion in a stream, beach, or glacial deposit; age cannot be determined visually.

Uses & applications

Common material for aggregate, landscaping, construction fill, and occasionally decorative stone; this ordinary pebble has little jewelry use.

Geological facts

The distinction between sandstone and quartzite requires a hardness or texture test: quartzite commonly scratches glass and breaks across grains, while sandstone often sheds grains or breaks around them.

Field identification & locations

Common worldwide, especially in quartz-rich river gravels and beaches. A hand lens, glass-scratch test, and inspection for visible sand grains or mica would improve identification; avoid destructive testing on valuable specimens.