sedimentary

Tuffaceous sandstone or volcanic tuff

Lithic/feldspathic tuffaceous sandstone; composition likely quartz, feldspar, volcanic ash, and lithic fragments

AI-generated identification · may be incorrect

Light tan, fine- to medium-grained, porous, and weakly layered with dark grains; dull to earthy luster and no visible crystal cleavage. Typical hardness is about 4–6 Mohs, with moderate to low specific gravity (~2.1–2.5).

Identified August 29, 2026More sedimentary →

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At a glance

Common name: Tuffaceous sandstone or volcanic tuff
Scientific name: Lithic/feldspathic tuffaceous sandstone; composition likely quartz, feldspar, volcanic ash, and lithic fragments
Category: sedimentary
Identified: August 29, 2026
Method: Standard

AI Estimated Value

Typically $1–$10 for a hand-sized common specimen; locality-labeled or unusually textured examples may sell for $10–$30.

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 formed from volcanic ash and sand deposited in layers, then compacted and cemented; alternatively, it may be a welded or reworked volcanic tuff. Exact age cannot be determined from the image and depends on its geologic locality.

Uses & applications

Used locally as building stone, aggregate, and decorative rock; attractive pieces may be collected but are generally not a jewelry material.

Geological facts

The dark specks may be volcanic rock fragments, biotite, or iron-stained minerals. The rounded shape is probably from natural stream or shoreline abrasion rather than its original formation.

Field identification & locations

Look for visible bedding, abundant pores, earthy texture, and abundant volcanic fragments; it should not fizz strongly in dilute hydrochloric acid unless carbonate cement is present. Common in volcanic basins, ash-flow deposits, and sedimentary formations near volcanoes.