paralaurionite

{{infobox mineral | name = Paralaurionite | boxwidth = | boxbgcolor = | image = Paralaurionite.jpg | imagesize = | alt = | caption = Platey clear paralaurionite crystals from slag in the Thorikos area, Lavrion, Attica, Greece | category = Halide mineral | formula = PbCl(OH) | IMAsymbol = Plri | molweight = | strunz = 3.DC.05 | dana = | system = Monoclinic | class = Prismatic (2/m) (same H-M symbol) | symmetry = C2/m | unit cell = a = 10.865(4) Å, b = 4.006(2) Å, c = 7.233(3) Å; β = 117.24(4)°; Z = 4 | color = Colorless, white, pale greenish, yellowish, yellow-orange, rarely violet | colour = | habit = Elongated tabular crystals | twinning = Contact twinning on {100} | cleavage = Perfect on {001} | fracture = | tenacity = Flexible, non-elastic | mohs = 3 | luster = Subadamantine | streak = | diaphaneity = Transparent to translucent | gravity = 6.05–6.15 | density = | polish = | opticalprop = Biaxial (−) | refractive = nα = 2.050 nβ = 2.150 nγ = 2.200 | birefringence = δ = 0.150 | pleochroism = Visible | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | prop1 = | prop1text = | references = }} Paralaurionite is a colorless mineral consisting of a basic lead chloride PbCl(OH) that is dimorphous with laurionite. It is a member of the matlockite group. The name is derived from para-, the Greek for "near", and laurionite, because of its polymorphic relationship to it. Bright, yellow tips of thorikosite can form on paralaurionite crystals and paralaurionite may also be intergrown with mendipite.

==Occurrence== It was first described in 1899 for an occurrence in slag in Laurium, Attica, Greece. In 1952 an occurrences of it was reported from the Mammoth Mine, Arizona.