Curite

{{infobox mineral | name = Curite | category = Oxide mineral | boxwidth = | boxbgcolor = | image = Curit - Shinkolobwe.jpg | imagesize = 260px | alt = | caption = Orange-red curite needles from Shinkolobwe mine, Katanga Province, Democratic Republic of the Congo | formula = Pb 3 [(UO 2 ) 4 O 4 (OH) 3 ] 2 ·2 H 2 O | IMAsymbol = Cui | molweight = | strunz = 4.GB.55 | system = Orthorhombic | class = orthorhombic-dipyramidal; 2/m 2/m 2/m | symmetry = Pnam | unit cell = a = 12.551 Å, b = 13.02 Å, c = 8.40 Å; Z = 2 | color = red, reddish orange, brownish yellow. | colour = | habit = needles, acicular, massive, compact earthy. | twinning = | cleavage = {100}, imperfect} | fracture = uneven | tenacity = brittle | mohs = 4-5 | luster = adamantine | streak = orange | diaphaneity = transparent | gravity = | density = measured: 6.98–7.4; calculated: 7,37 | polish = | opticalprop = biaxial (-) | refractive = n α = 2.060 n β = 2.110 n γ = 2.150 | birefringence = 0.090 | pleochroism = Visible: X = b = pale yellow, Y = a = light red-orange, Z = c = dark red-orange | 2V = 70° (measured); 80° (calculated) | dispersion = | extinction = | length fast/slow = | fluorescence= | absorption = | melt = | fusibility = | diagnostic = | solubility = | other = Radioactive | alteration = | references = }} Curite is a rare mineral with the chemical composition Pb 3 [(UO 2 ) 4 O 4 (OH) 3 ] 2 ·2 H 2 O.…

{{infobox mineral | name = Curite | category = Oxide mineral | boxwidth = | boxbgcolor = | image = Curit - Shinkolobwe.jpg | imagesize = 260px | alt = | caption = Orange-red curite needles from Shinkolobwe mine, Katanga Province, Democratic Republic of the Congo | formula = Pb 3 [(UO 2 ) 4 O 4 (OH) 3 ] 2 ·2 H 2 O | IMAsymbol = Cui | molweight = | strunz = 4.GB.55 | system = Orthorhombic | class = orthorhombic-dipyramidal; 2/m 2/m 2/m | symmetry = Pnam | unit cell = a = 12.551 Å, b = 13.02 Å, c = 8.40 Å; Z = 2 | color = red, reddish orange, brownish yellow. | colour = | habit = needles, acicular, massive, compact earthy. | twinning = | cleavage = {100}, imperfect} | fracture = uneven | tenacity = brittle | mohs = 4-5 | luster = adamantine | streak = orange | diaphaneity = transparent | gravity = | density = measured: 6.98–7.4; calculated: 7,37 | polish = | opticalprop = biaxial (-) | refractive = n α = 2.060 n β = 2.110 n γ = 2.150 | birefringence = 0.090 | pleochroism = Visible: X = b = pale yellow, Y = a = light red-orange, Z = c = dark red-orange | 2V = 70° (measured); 80° (calculated) | dispersion = | extinction = | length fast/slow = | fluorescence= | absorption = | melt = | fusibility = | diagnostic = | solubility = | other = Radioactive | alteration = | references = }} Curite is a rare mineral with the chemical composition Pb 3 [(UO 2 ) 4 O 4 (OH) 3 ] 2 ·2 H 2 O. It is therefore a hydrated lead uranyl oxide, which forms red needles or orange, massive aggregates. Curite crystallizes orthorhombically in space group Pnama with the lattice parameters a = 12.56 Å; b = 13.02 Å and c = 8.40 Å and two formula units per unit cell. The crystal structure consists of layers of corner- and edge-sharing uranyl polyhedra, in which the uranyl cation shows both pentagonal-bipyramidal and square-bipyramidal coordination. The lead cations connect these layers by coordinating to the oxygen atoms of uranyl group.

Text derived from https://en.wikipedia.org/w/index.php?oldid=1358808597 under CC BY-SA 4.0; modifications have been made.