sedimentary

Rounded quartz-rich cobble

Likely quartzite or siliceous sandstone; predominantly microcrystalline SiO₂ with possible feldspar and iron-oxide staining

AI-generated identification · may be incorrect

Hardness about 6.5–7 if quartzite, or 5–7 if sandstone; tan-gray, dull to slightly sugary luster, granular texture, and no obvious cleavage. Rounded shape indicates water abrasion; apparent pale patches may be quartz-rich cement or weathering.

Identified August 10, 2026More sedimentary →

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At a glance

Common name: Rounded quartz-rich cobble
Scientific name: Likely quartzite or siliceous sandstone; predominantly microcrystalline SiO₂ with possible feldspar and iron-oxide staining
Category: sedimentary
Identified: August 10, 2026
Method: Standard

AI Estimated Value

Usually $1–$10 as an ordinary cobble; approximately $10–$30 if unusually aesthetic, locality-specific, or confirmed as a collectible specimen.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Formation & geological history

Likely a naturally weathered sedimentary cobble, formed from cemented sand or metamorphosed sandstone and later transported by a stream or shoreline. Its precise geological age and provenance cannot be determined from the image.

Uses & applications

Primarily a beach/river collectible, teaching specimen, or landscaping stone; generally little commercial or jewelry value unless it proves to be unusually attractive quartzite.

Geological facts

Quartz-rich rocks commonly resist weathering and become rounded cobbles. A glassy streak or visible interlocking quartz grains would support quartzite; fizzing with dilute acid would suggest carbonate cement instead.

Field identification & locations

Common in river gravels, beaches, glacial deposits, and exposed sedimentary terrains. Check a fresh surface with a steel nail or glass: quartzite scratches glass and shows little porosity, while sandstone is usually more visibly granular and porous.