linarite

{{Infobox mineral | name = Linarite | boxwidth = | boxbgcolor = | image = Linarite-162465.jpg | imagesize = 260px | alt = | caption = | category = Sulfate minerals | formula = PbCu[(OH)2|SO4] | IMAsymbol = Lna | molweight = | strunz = 7.BC.65 | dana = | system = Monoclinic | class = Prismatic (2/m) (same H-M symbol) | symmetry = P21/m | unit cell = a = 9.701(2), b = 5.65 c = 4.69 [Å]; β = 102.65°; Z = 2 | color = Deep azure blue | colour = | habit = Crystals elongated and tabular; in crusts and aggregates | twinning = Common on {100}, also on {001} | cleavage = Perfect on {100}, imperfect on {001} | fracture = Conchoidal | tenacity = | mohs = 2.5 | luster = Sub-adamantine, vitreous | streak = Pale blue | diaphaneity = Transparent, translucent | gravity = 5.3 – 5.5 | density = | polish = | opticalprop = Biaxial (−) | refractive = nα = 1.809 nβ = 1.838 nγ = 1.859 | birefringence = δ = 0.050 | pleochroism = X = pale blue; Y = blue; Z = Prussian blue | 2V = Measured: 80° | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | references = }}

Linarite is a somewhat rare, crystalline mineral that is known among mineral collectors for its unusually intense, pure blue color. It is formed by the oxidation of galena and chalcopyrite and other copper sulfides. It is a combined copper lead sulfate hydroxide with formula PbCuSO4(OH)2. Linarite occurs as monoclinic prismatic to tabular crystals and irregular masses. It is easily confused with azurite, but does not react with dilute hydrochloric acid as azurite does. It has a Mohs hardness of 2.5 and a specific gravity of 5.3 – 5.5.