Parnauite is a very rare secondary copper arsenate–sulfate mineral. It forms near the Earth's surface in oxidized zones of various copper deposits. These copper minerals are altered by oxygen-rich water and new minerals grow as a thin coatings or small crystal clusters. Parnauite is typically blue-green to green and commonly occurs as tiny bladed crystals in fan-shaped sprays or rosettes. It may also appear as scaly crusts or crystal-like surface films.
{{Infobox mineral | name = Parnauite | boxwidth = | boxbgcolor = #228B22 | image = Parnauite-89334.jpg | caption = Parnauite | category = Arsenate minerals | formula = Cu9(AsO4)2(SO4)(OH)10 · 7H2O | IMAsymbol = Pna | molweight = | strunz = 8.DF.35 | dana = 43.5.13.1 | system = Orthorhombic | unit cell = 641.15 ų (calculated) | color = Pale blue, green, dark green, blue-green, yellow-green | habit = Fans and rosettes of lath-like crystals; fibrous; scaly crusts | cleavage = Good | mohs = 2 | streak = Greenish white | gravity = 3.09 | opticalprop = Biaxial (−) | refractive = nα = 1.680(3), nβ = 1.704(3), nγ = 1.712(3) | birefringence = δ = 0.032 | pleochroism = Weak | 2V = Measured: 60°(5); calculated: 58° | dispersion = r > v (strong) | extinction = Optic plane parallel to {100}.X = b, Y = a, Z = c. | length fast/slow = | fluorescence = None | impurities = P, C, Al | references =
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Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).