metamorphic
Iridescent quartz-bearing rock, likely bornite/chalcopyrite-bearing quartzite
Quartz (SiO₂) with probable chalcopyrite (CuFeS₂) and/or bornite (Cu₅FeS₄)
AI-generated identification · may be incorrectHardness approximately 6–7 for the quartz matrix; metallic sulfides are softer (about 3–4). The specimen is pale gray-tan with purple, blue, bronze, and gold tarnish, displaying vitreous to dull luster and a massive, nonfoliated texture.
Identified More metamorphic →
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Physical properties
Hardness approximately 6–7 for the quartz matrix; metallic sulfides are softer (about 3–4). The specimen is pale gray-tan with purple, blue, bronze, and gold tarnish, displaying vitreous to dull luster and a massive, nonfoliated texture.
Formation & geological history
Likely a quartz-rich metamorphic or hydrothermal vein rock formed when silica-rich fluids deposited quartz and copper-iron sulfides, later altered at the surface. Exact geological age cannot be determined from the photograph.
Uses & applications
Used mainly as a mineral-collecting specimen or ornamental stone; copper sulfides may be economically important in ore deposits, but this piece is unlikely to have significant commodity value.
Geological facts
Purple-blue-gold iridescence commonly results from thin oxidation films on chalcopyrite or bornite, sometimes sold commercially as “peacock ore.” Surface color alone is not diagnostic and may be enhanced artificially.
Field identification & locations
Look for a hard, quartz-rich matrix with brassy metallic grains and colored tarnish; a streak test, hardness test, and copper-sulfide identification would confirm it. Common in hydrothermal copper deposits worldwide.
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