mineral

Blue slag-like mineral specimen, possibly bornite or chalcopyrite

Tentatively bornite (Cu5FeS4) or iridescent chalcopyrite (CuFeS2)

AI-generated identification · may be incorrect

Dark metallic blue with strongly iridescent surfaces and irregular fracture; likely Mohs 3–4, metallic luster, opaque, and relatively dense. The photograph is insufficient to distinguish a natural sulfide from blue-colored industrial slag.

Identified September 18, 2026More mineral →

Explore Blue slag-like mineral specimen, possibly bornite or chalcopyrite in the encyclopedia →

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Physical properties

Formation & geological history

Copper sulfides form in hydrothermal veins and disseminated ore deposits, generally in ancient igneous or metamorphic terrains; bornite commonly develops through alteration of copper ores. If slag, it is a modern furnace by-product rather than a geological rock.

Uses & applications

Natural material is collected as a mineral specimen and may indicate copper ore; chalcopyrite and bornite are important copper sources. Slag has little gem or commercial value but may be collected as industrial material.

Geological facts

Bornite is famously called “peacock ore” when its surface tarnishes purple, blue, and green. A bright cobalt-blue appearance can also result from artificial coating or oxidation of copper-bearing material.

Field identification & locations

Check for a metallic streak, high density, copper sulfide odor only when heated, and softness relative to quartz; avoid acid or destructive tests. Common sources include Arizona, Montana, Peru, and Mexico.