sedimentary

Weathered porous sandstone or tuff

Indeterminate siliciclastic rock, likely quartz-rich sandstone; possibly volcanic tuff

AI-generated identification · may be incorrect

Tan to brown, very rough and porous surface with an erosional cavity; likely Mohs hardness about 5–7 if sandstone, or 3–6 if tuff. Dull to earthy luster; individual grains or ash fragments are not resolvable in the image, and cleavage is absent.

Identified August 27, 2026More sedimentary →

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At a glance

Common name: Weathered porous sandstone or tuff
Scientific name: Indeterminate siliciclastic rock, likely quartz-rich sandstone; possibly volcanic tuff
Category: sedimentary
Identified: August 27, 2026
Method: Standard

AI Estimated Value

Typically $1–$20 as an unattributed specimen; notable fossiliferous, architectural, or unusual volcanic examples may sell for $20–$100.

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

Most consistent with lithified sand deposited by water or wind and cemented by silica, calcite, or iron oxides; alternatively, compacted volcanic ash. Age cannot be determined from the photograph; weathering enlarged the visible cavity.

Uses & applications

Sandstone is used for building stone, paving, walls, and aggregate; tuff is used as lightweight building material and occasionally for carving. This heavily weathered fragment has little commercial value.

Geological facts

The cavity may reflect differential weathering around a softer grain, pebble, fossil fragment, or vesicle. Iron-oxide staining commonly produces the yellow-brown coloration.

Field identification & locations

Look for visible rounded quartz grains and bedding to confirm sandstone; ash-sized particles, flattened pumice, or volcanic fragments would favor tuff. Common settings include deserts, river deposits, cliffs, and volcanic terrains.