sedimentary

Weathered sandstone or siltstone cobble

Clastic sedimentary rock, probably quartz-rich sandstone; exact identification requires testing

AI-generated identification · may be incorrect

Pale tan-gray, dull earthy luster, fine to medium grain, massive texture, and rounded weathered surfaces; likely Mohs hardness 5–7, with no obvious cleavage. The apparent dark fragment may be attached matrix or a separate piece, so mineral composition is uncertain.

Identified September 20, 2026More sedimentary →

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At a glance

Common name: Weathered sandstone or siltstone cobble
Scientific name: Clastic sedimentary rock, probably quartz-rich sandstone; exact identification requires testing
Category: sedimentary
Identified: September 20, 2026
Method: Standard

AI Estimated Value

About $1–$10 as an unattributed common specimen; potentially $20–$100+ if a documented locality, fossil, or unusual texture is confirmed.

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

Formed by compaction and cementation of sand- or silt-sized sediment, probably millions to hundreds of millions of years ago; surface rounding indicates erosion and transport or prolonged weathering.

Uses & applications

Common sandstone is used for building stone, paving, landscaping, aggregate, and occasionally carving; this specimen has little commercial value unless locality or fossil content is established.

Geological facts

The photograph alone cannot reliably distinguish sandstone from weathered siltstone, tuff, or a concretion. A hand lens, streak test, acid test, and fresh broken surface would improve identification.

Field identification & locations

Look for visible quartz grains, gritty texture, sedimentary layering, and weak reaction to dilute hydrochloric acid; compare its hardness with a steel nail and glass. Common worldwide, especially in sedimentary basins.