sedimentary

Conglomerate (possibly fossiliferous limestone breccia)

Polymictic conglomerate; clasts commonly quartz, chert, and carbonate cement (exact identification requires testing)

AI-generated identification · may be incorrect

Gray-green, rounded to subangular pebbles in a lighter cement; dull to slightly earthy luster, no visible crystal fabric, and variable hardness around 3–7 Mohs depending on clasts. Carbonate cement may fizz with dilute hydrochloric acid.

Identified September 1, 2026More sedimentary →

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At a glance

Common name: Conglomerate (possibly fossiliferous limestone breccia)
Scientific name: Polymictic conglomerate; clasts commonly quartz, chert, and carbonate cement (exact identification requires testing)
Category: sedimentary
Identified: September 1, 2026
Method: Standard

AI Estimated Value

About $5–$30 as a common hand specimen; $30–$100+ if confirmed fossiliferous, unusually patterned, or from a documented locality.

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 when water-rounded gravel was deposited, buried, compacted, and cemented by silica or calcite; age and environment cannot be determined from the photograph alone. The irregular clasts could alternatively indicate a carbonate breccia or fossil-rich limestone.

Uses & applications

Used locally as decorative stone, landscaping rock, aggregate, and occasionally building stone; generally has little gem or collector value unless fossil-bearing or unusually attractive.

Geological facts

Conglomerates record ancient rivers, beaches, alluvial fans, or high-energy shorelines. Rounded clasts indicate transport and abrasion before lithification.

Field identification & locations

Identify by examining clast shape, testing acid reaction, and checking whether individual grains scratch glass or are scratched by a steel nail. Common worldwide in sedimentary basins; the specimen’s exact locality is needed for precise identification.