sedimentary

Weathered graywacke or sandstone with a dark mineral-rich vein

Likely lithic graywacke/sandstone; dark material may be quartz, iron-manganese oxide, or sulfide mineralization

AI-generated identification · may be incorrect

Tan-gray, fine- to medium-grained, dull earthy luster, apparently weakly cemented and fractured; hardness likely about 3–7 depending on cement and dark vein. No diagnostic crystal faces or cleavage are visible, and the specimen may be naturally weathered or cut.

Identified September 19, 2026More sedimentary →

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At a glance

Common name: Weathered graywacke or sandstone with a dark mineral-rich vein
Scientific name: Likely lithic graywacke/sandstone; dark material may be quartz, iron-manganese oxide, or sulfide mineralization
Category: sedimentary
Identified: September 19, 2026
Method: Standard

AI Estimated Value

About $1–$10 as an ordinary specimen; potentially $10–$30 if the dark vein proves to be an attractive or unusual mineralization.

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 deposited as sand or volcanic-rich sediment, then compacted and cemented; the dark zone formed later as a fracture-filling vein or altered layer. Exact age and formation environment cannot be determined from the photograph.

Uses & applications

Common sandstone is used for building stone, aggregate, and landscaping; graywacke is mainly crushed for road base. This small, weathered piece has little jewelry or commercial value.

Geological facts

Graywacke commonly contains poorly sorted rock fragments and feldspar in a muddy matrix, often indicating submarine turbidity-current deposition. Dark coatings may be manganese/iron oxides rather than a distinct ore mineral.

Field identification & locations

Look for gritty grains, poorly sorted texture, and bedding or sedimentary laminations; a glassy vein that scratches glass suggests quartz. Common in folded mountain belts, submarine-fan deposits, and many coastal regions.