diaboleite

{{Infobox mineral | name = Diaboleite | category = Halide mineral | boxwidth = | boxbgcolor = | image = Diaboleite-21675.jpg | imagesize = 260px | caption = | formula = Pb2CuCl2(OH)4 | IMAsymbol = Dbol | strunz = 3.DB.05 | dana = 10.6.1.1 | system = Tetragonal | class = Ditetragonal pyramidal (4mm) H-M symbol: (4mm) | symmetry = P4mm | unit cell = a = 5.880, c = 5.500 Å, Z = 1 | molweight = | color = Blue | habit = As square tabular crystals, thin plates, massive | twinning = | cleavage = Perfect on {001} | fracture = Conchoidal | tenacity = Brittle | mohs = 2.5 | luster = Adamantine, pearly on cleavages | polish = | refractive = nω = 1.980, nε = 1.850 | opticalprop = Uniaxial (−) | birefringence = δ = 0.130 | 2V = | dispersion = | pleochroism = | fluorescence= | absorption = O > E, in thick fragments | streak = Pale blue | gravity = | density = 5.41 to 5.43 g/cm3 | melt = | fusibility = | diagnostic = | solubility = Completely soluble in nitric acid | diaphaneity = Transparent to translucent | other = | references = }} Diaboleite is a blue-colored mineral with formula Pb2CuCl2(OH)4. It was discovered in England in 1923 and named diaboleite, from the Greek word διά and boleite, meaning "distinct from boleite". The mineral has since been found in a number of countries.

==Description== thumb|left|Diaboleite crystal from a slag occurrence in the Laurium District, [[Attica, Greece (size: less than 1 mm)]] Diaboleite is deep blue in color and pale blue in transmitted light. The mineral occurs as tabular crystals up to in size, as subparallel aggregates, or it has massive habit. Vicinal forms of the tabular crystals have a square or octagonal outline and rarely exhibit pyramidal hemihedralism.