sedimentary

Pyrite-bearing dark shale or slate

Fine-grained carbonaceous shale/slate with disseminated pyrite (FeS₂); exact host rock is uncertain from the photo

AI-generated identification · may be incorrect

Dark blue-black, fine-grained matrix with brassy metallic flecks; the flecks may be pyrite. Pyrite has Mohs hardness 6–6.5, cubic crystals, and no cleavage; the host’s hardness and cleavage depend on whether it is shale or slate.

Identified October 16, 2026More sedimentary →

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At a glance

Common name: Pyrite-bearing dark shale or slate
Scientific name: Fine-grained carbonaceous shale/slate with disseminated pyrite (FeS₂); exact host rock is uncertain from the photo
Category: sedimentary
Identified: October 16, 2026
Method: Standard

AI Estimated Value

About $2–$20 for a small, common hand specimen; locality, crystal quality, and confirmed identification affect value.

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

Fine mud accumulated in low-oxygen water and lithified; pyrite formed where iron and sulfur reacted in oxygen-poor sediment. Slate, if present, would reflect later low-grade metamorphism; age and locality cannot be determined visually.

Uses & applications

Mostly a collector specimen or geological teaching sample; pyrite and shale are not generally valuable in this form.

Geological facts

Pyrite is commonly called “fool’s gold,” but its brassy color and brittle fracture differ from gold.

Field identification & locations

Look for a fine, layered or fissile dark matrix and hard, brassy grains; pyrite can leave a dark greenish-black streak. The visible flecks are suggestive, not conclusive—confirm with a streak or hardness test.