mineral

Weathered copper-bearing sulfide rock (likely bornite/chalcopyrite)

Bornite (Cu5FeS4) and/or chalcopyrite (CuFeS2), with oxidation tarnish

AI-generated identification · may be incorrect

Hardness about 3–4 Mohs; dark bronze to brassy metallic surface with iridescent blue-green, purple, and turquoise tarnish (“peacock ore”); massive, opaque, metallic luster, no obvious cleavage. Specific gravity commonly 4.1–4.3.

Identified September 10, 2026More mineral →

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At a glance

Common name: Weathered copper-bearing sulfide rock (likely bornite/chalcopyrite)
Scientific name: Bornite (Cu5FeS4) and/or chalcopyrite (CuFeS2), with oxidation tarnish
Category: mineral
Identified: September 10, 2026
Method: Standard

AI Estimated Value

Approximately $5–$30 for a small common specimen; $30–$100+ if naturally iridescent, well-crystallized, or locality-documented.

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

Forms in hydrothermal copper deposits and disseminated sulfide ores, typically in igneous-related veins; the colorful surface develops through oxidation and weathering over geological time.

Uses & applications

Copper ores are mined for electrical wiring, plumbing, alloys, and industrial use; attractive polished pieces are sold as mineral specimens, though many commercial “peacock ore” pieces are artificially treated.

Geological facts

True bornite is commonly called peacock ore, but chalcopyrite is frequently marketed under the same name and treated with acid to intensify colors.

Field identification & locations

Look for unusually high density, metallic sheen, brassy bronze beneath the tarnish, and a dark gray streak; copper-bearing sulfides may leave a sulfurous odor when freshly fractured. Common in Arizona, Montana, Peru, Chile, and other major copper districts.