Cornwallite
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Cornwallite is an uncommon copper arsenate mineral with formula Cu₅(AsO₄)₂(OH)₄. It forms a series with the phosphate pseudomalachite and is a dimorph of the triclinic cornubite. It is a green monoclinic mineral which forms as radial to fibrous... Wikipedia
Crystal class: Prismatic (2/m); (same H-M symbol)
Crystal habit: Microcrystalline radial fibrous, botryoidal to globular crusts
Crystal system: Monoclinic