New Evidence of the Brizziite, Sodium Antimonate from the Central Paratethys Sea Strata in Poland

Abstract

Brizziite, a rare sodium antimonate (NaSb5+O3), and fluorcalcioroméite ((Ca,Na)2Sb5+2O6F), have been identified in two boreholes (Pasternik and Włosienica) which are situated 50 km apart. Both wells are located west of Krakow, Poland, and were drilled in the Miocene strata of the Paratethys Sea (a remnant of the Tethys Ocean). The Sb minerals are scattered in a solidified light blue silica gel within marls and layered clays. They occur most often as anhedral grains up to 20 μm in size. The presence of these phases was confirmed by Raman spectroscopy (RS) and X-ray diffraction (XRD). The brizziite from this study represents a secondary mineral after the alteration of roméite within a supergene zone, or crystallization from Sb-rich solutions derived by the leaching of the weathered primary roméite. Hence, the calcium and fluorine admixtures in their composition, determined by EPMA, indicate intergrowths of brizziite and roméite on the micro- to crypto-scale. The presence of the antimony in the study area is related to rejuvenated Old-Paleozoic polymetallic ore-mineralization occurring in the basement of the Krakow-Silesia Monocline. The phenomenon of the repeatability of brizziite in Pasternik and Włosienica, distant by several tens of kilometers, can be explained by the following three steps: (i) the penetration of the chloride ions from the drying up seawaters of the Paratethys Sea into the Miocene groundwater system, (ii) the mobilization of Sb5+ in the form of chloride complexes, and, finally, (iii) the transportation of the Sb-bearing solutions within the marly and clay sediments.