gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1957.031.238.01 Götzenite and Combeite, Two New Silicates from the Belgian Congo Sahama Th. G. Hytönen Kai M.A. Institute of Geology, University of Helsinki, Finland 9 1957 31 238 503 510 Copyright © 1957, The Mineralogical Society 1957 Summary

A nephelinite from the extinct volcano Mt. Shaberu, North Kivu, Belgian Congo, contains two new minerals: Götzenite is triolinic with a 10·93, b 7·32, c 5·74 Å, α 90°, β 100°, γ 120°; the unit-cell contents approximate to (Ca,Na,Al)7 (Si,Ti)5O15F3·5, and the optical constants are α 1·660, β 1·662, γ 1·670, 2Vγ 52°; sp.gr. 3·138. Götzenite is related to the rinkite series, and, less closely, to wollastonite and pectolite. Combeite is rhombohedral, space-group R3m, R32, or R¯3m, a 10·43, c 13·14 Å., the unit cell containing approximately 3[Na4(Ca,Al,Fe)3Si6O15(O,OH,F)2]; optically uniaxial positive, ε = ω = 1·598±0·002; sp.gr. 2·844.