Hostname: page-component-77c89778f8-vpsfw Total loading time: 0 Render date: 2024-07-20T07:25:20.811Z Has data issue: false hasContentIssue false

Götzenite and combeite, two new silicates from the Belgian Congo

Published online by Cambridge University Press:  14 March 2018

Th. G. Sahama
Affiliation:
Institute of Geology, University of Helsinki, Finland
Kai Hytönen
Affiliation:
Institute of Geology, University of Helsinki, Finland

Summary

A nephelinite from the extinct volcano Mt. Shaberu, North Kivu, Belgian Congo, contains two new minerals: Götzenite is triclinic 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.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1957

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)