igneous
Copper-bearing porphyritic rock (likely bornite/chalcopyrite ore)
Altered porphyritic volcanic rock with copper sulfides, chiefly bornite (Cu₅FeS₄) and/or chalcopyrite (CuFeS₂)
AI-generated identification · may be incorrectDark gray to reddish-brown, coarse porphyritic texture with metallic to submetallic patches and possible green-blue oxidation products; individual minerals are commonly Mohs 3–4, with sulfides showing uneven fracture rather than prominent cleavage.
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Physical properties
Dark gray to reddish-brown, coarse porphyritic texture with metallic to submetallic patches and possible green-blue oxidation products; individual minerals are commonly Mohs 3–4, with sulfides showing uneven fracture rather than prominent cleavage.
Formation & geological history
Likely hydrothermal alteration of volcanic rock in a copper-ore deposit, formed when hot mineral-rich fluids filled fractures and replaced host rock; age depends on locality and cannot be determined from the image.
Uses & applications
Primarily collected as an ore specimen and historically mined for copper; generally unsuitable for jewelry or construction because it is dense, heterogeneous, and may weather or oxidize.
Geological facts
Bornite is known as “peacock ore” when its surface develops iridescent blue, purple, and bronze tarnish. Fresh chalcopyrite is brass-yellow, while oxidation can produce blue-green copper minerals.
Field identification & locations
Look for metallic sulfide grains, reddish-brown host rock, heavy weight, and possible blue-green staining; a streak, hardness, magnetism, and chemical tests are needed for confident identification. Common in porphyry-copper and hydrothermal deposits worldwide.
