Holotype material is deposited in the mineralogical collection of the Museo di Storia Naturale, Università di Pisa, Via Roma 79, Calci (Pisa, Italy), under catalogue number 19,927. Zoisite-(Pb) was discovered in the Jakobsberg manganese-iron oxide deposit, Filipstad district, Värmland County, Sweden. Zoisite-(Pb) is isostructural with zoisite, and its crystal chemical relationships with zoisite and with synthetic Sr and Pb zoisites are discussed. The new mineral and its name were approved by the IMA-CNMMNC (IMA-2021-025). We report in the present paper the occurrence of the new mineral zoisite-(Pb), with ideal formula CaPbAl 3(SiO 4)(Si 2O 7)O(OH). Despite its close relationships with the epidote supergroup, zoisite, given its orthorhombic symmetry, is not included in the former supergroup. Clinozoisite belongs to the epidote supergroup, which includes phases with monoclinic symmetry, distributed in the allanite, clinozoisite, and dollaseite groups, together with the mineral åskagenite-(Nd). According to literature studies, zoisite and clinozoisite can be considered as the iron-poor, high-temperature and the iron-rich, low-temperature phase, respectively. They are polymorphs, with ideal formula Ca 2Al 3(SiO 4)(Si 2O 7)O(OH), with orthorhombic and monoclinic symmetry for zoisite and clinozoisite, respectively. Zoisite and clinozoisite are mixed anion silicates widespread in nature, in locally rock-forming phases in low- to medium-grade metamorphic rocks. The effects of the incorporation of Pb in the crystal structure of zoisite-(Pb), hancockite, and related synthetic and natural phases are described and discussed.
#POLYHEDRA TRANSPARENCY CRYSTALMAKER FULL#
A full chemical and Raman characterization of zoisite-(Pb) and of the Pb-bearing epidote hancockite is reported, together with an improved crystal structural model of hancockite, refined up to R 1 = 0.02 reflections with F o > 4σ( F o). Pb shows a stereochemically active lone pair leading to a lopsided distribution of its coordinating oxygens. Zoisite-(Pb) is isostructural with zoisite and its crystal structure was refined up to R 1 = 0.02 reflections with F o > 4σ( F o). Associated feldspars show one of the highest PbO contents (~7–8 wt%) found in nature. Zoisite-(Pb) is found as pale pink subhedral prisms elongated on, up to 0.3 mm in size, associated with calcite, celsian, diopside, grossular, hancockite, hyalophane, native lead, phlogopite, and vesuvianite. The new mineral zoisite-(Pb), ideally CaPbAl 3(SiO 4)(Si 2O 7)O(OH), was discovered in a sample from the Jakobsberg manganese-iron oxide deposit, Värmland, Sweden.
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