Ca-bearing phosphatian mimetite from Redziny, Lower Silesia, Poland
Gołębiowska, Bożena; Pieczka, Adam; Franus, Wojciech
published: Jan 18, 2002
Calcium-bearing mimetite-pyromorphite has been found in the weathering zone of the dispersed ore mineralization occurring within the contact zone between dolostones and amphibolites in Rędziny (E metamorphic cover of the Karkonosze granite massif, Lower Silesia, Poland). It is honey-yellow with slightly green tint, fills small caverns or fractures, forms massive accumulations or encrustations on earlier minerals, but also occurs as individual crystals up to 3 mm in size. The mean chemical composition of the mineral is: (Pb3.86Ca0.70Zn0.04Cd0.02Mn0.01Bi0.02Sb0.01Fe0.01Sn0.01)[(As1.54P1.14S0.31V<0.01)O11.69OH0.30|Cl1.01], and unit cell parameters are: a = 10.087(2) Å, c = 7.335(3) Å, V = 646.2(6) Å3 (the P63/m space group). X-ray and IR spectroscopic data have shown that it represents a transitional phase in the ternary system mimetite-pyromorphite-turneaureite. The mineral cooccurs with oxidized compounds of vanadium (mainly mottramite), Ca-Pb-Cu-Zn arsenates of the adelite group, hemimorphite, goethite, quartz and relicts of galena. Formation of the mineral is linked to hypergenic oxidation processes of primary ore mineralization and migration of lead, arsenate, phosphate and sulphate ions in a zone bordering the dolostone.