gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1982.046.340.07 Roeblingite: New Chemical Data Dunn Pete J. Norberg Julie A. Department of Mineral Sciences, Smithsonian Institution, Washington, DC 20560, USA Leavens Peter B. Department of Geology, University of Delaware, Newark, Delaware 19711, USA 9 1982 46 340 341 342 3 8 1981 Copyright © 1982, The Mineralogical Society 1982 Abstract

New chemical analyses of roeblingite from Franklin, New Jersey, and Långban, Sweden, are presented. The average composition of Franklin roeblingite is SiO2 24.9, CaO 23.8, SrO 2.4. MnO 2.4, PbO 30.2 SO3 10.4, H2O 6.13%, Sum = 100.23%. The data support space group C2/m and suggest the formula is (Ca,Sr)12 (Mn,Ca)2Pb4(SO4)4Si12O28(OH)20, if there is ordering on the site of rank 2.