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Cake day: June 7th, 2023

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  • 908musdf@lemmy.onetoGeology@lemmy.caRock ID Thread
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    2 years ago

    According to Mindat, this is the Lomas Bayas disctrict, and the most prominent mine appears to be the Fortuna de Cobre, in a copper porphyry deposit. I would normally reach for malachite first, but it is not listed as found at any of the mines, so your main options are brochantite or (surprise!) atacamite.

    Malachite can be eliminated for sure by testing with vinegar; it will effervesce slightly. Between brochantite and atacamite, there is considerable overlap in color, hardness, etc. You will have to get a lens and look for some crystals where the shape is distinct enough to determine if they are monoclinic (brochantite) or orthorhombic (atacamite).