conichalcite

{{Infobox mineral | name = Conichalcite | category = Arsenate minerals | boxwidth = 24 | boxbgcolor = | image = Conichalcite-Calcite-65643.jpg | imagesize = 260px | caption = A thin crust of conichalcite on a rock. | formula = CaCu(AsO4)(OH) | IMAsymbol = Con | molweight = | strunz = 8.BH.35 | dana = 41.5.1.2 | system = Orthorhombic | class = Disphenoidal (222) (same H-M symbol) | symmetry = P212121 | unit cell = a = 7.39(1) Å, b = 9.23(1) Å, c = 5.83(1) Å; V = 397.66 Å³; Z = 4 | color = Grass-green to yellowish green, pistachio-green, emerald-green; may be zoned; light green to yellowish green in transmitted light. | habit = Crusts of acicular to almost fibrous crystals. Also as botryoidal masses and compact crusts. | twinning = Rare on {001} | cleavage = Absent | fracture = Uneven | tenacity = Brittle | mohs = 4.5 | luster = Vitreous, greasy | refractive = nα = 1.778 – 1.800 nβ = 1.795 – 1.831 nγ = 1.801 – 1.846 | opticalprop = Biaxial (+/−) | birefringence = δ = 0.023 – 0.046 | pleochroism = Visible | 2V = | dispersion = Strong r 4)(OH), is a relatively common arsenate mineral related to duftite (PbCu(AsO4)(OH)). It is green, often botryoidal, and occurs in the oxidation zone of some metal deposits. It occurs with limonite, malachite, beudantite, adamite, cuproadamite, olivenite and smithsonite.

== Formation == thumb|left|Mat of conichalcite spheres on limonite base from the Ojuela Mine, Mapimí, Durango, Mexico (size: 10.4 x 8.9 x 4.2 cm) Conichalcite forms in the oxidation zones of copper orebodies. Here groundwater enriched with oxygen reacts with copper sulfide and copper oxide to produce an array of minerals such as malachite, azurite and linarite. Conichalcite is often found encrusted on to limonitic rocks that have yellow to red colors.