Chemical Composition and Physical Properties of Lithium-Iron Micas from the Krušné Hory (Erzgebirge), Czechoslovakia and Germany. Part B: Cell Parameters and Optical Data

M. Rieder, A. Píchová, M. Fassová, E. Fediuková and P. Černý
Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, Maryland1
Geological Survey of Czechoslovakia, Praha
Geological Institute, Czechoslovak Academy of Sciences, Praha
1Present address: Ústav geologických věd University Karlovy, Albertov 6, Praha 2, Czechoslovakia.

Summary: Unit-cell dimensions and refractive indices of lithium-iron micas decrease with decreasing iron and increasing lithium. Indices β and γ as well as parameters a and b can be used to estimate the composition of lithium-iron micas but basal spacing and 2Vα are poor indicators of composition.

The chemical composition of natural lithium-iron micas from the Krušné hory and the Erzgebirge along the Czechoslovak—German border was discussed in Part A of this study (Rieder et al., 1970). It was concluded that the composition and crystallography of these micas fit best the series siderophyllite-polylithionite. The compositions were expressed by the ratio A′ = LR/(LR+‘Fe’). In this expression, LR is the subscript value of Li or octahedral R3+ (whichever is the smaller) in the crystallochemical formula, ‘Fe’ is the sum of the values in the formula of Fe2+ and Mn2+. A′ therefore defines the position of a particular mica on the siderophyllite-polylithionite join. This paper deals with the correlation between composition, cell dimensions, and refractive indices.

Mineralogical Magazine; June 1971 v. 38; no. 294; p. 190-196; DOI: 10.1180/minmag.1971.038.294.08
© 1971, The Mineralogical Society
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