The crystal structure of stilpnomelane. Part III: Chemistry and physical properties
- 1 September 1978
- journal article
- Published by Mineralogical Society in Mineralogical Magazine
- Vol. 42 (323) , 361-368
- https://doi.org/10.1180/minmag.1978.042.323.06
Abstract
Summary: Full chemical analysis, cell dimensions, γ refractive index, density, and infra-red absorption spectrum have been determined for fourteen stilpnomelanes. Coupled with data from previously described material and electron probe analyses of three further samples, the new information shows that γ = 1·616+0·0047 Fe3+ −0·0037 Mg; substitution of Mn for Fe appears to have little effect on γ. For ferrostilpnomelane, D = 2·85−0·011 Mg, for ferristilpnomelane, D = 2·89−0·011 Mg. Cell dimensions clearly distinguish ferro-, ferri-, and man-ganstilpnomelanes; for ferri-stilpnomelane a = 22·03−0·00446 Mg−0·00786 Fe3+ (Å). A convenient approximation to the structural formula using a ⅛ subcell, is K0·6(Mg, Fe2+Fe3+)6Si8Al(O,OH)27 2–4 H2O.Keywords
This publication has 7 references indexed in Scilit:
- A note on some Dalradian stilpnomelanes and their oxidationMineralogical Magazine, 1976
- Microcoulometric measurement of water in mineralsAnalytica Chimica Acta, 1972
- The crystal structure of stilpnomelane. Part II. The full cellMineralogical Magazine, 1972
- An accurate X-ray spectrographic method for the analysis of a wide range of geological samplesGeochimica et Cosmochimica Acta, 1969
- On stilpnomelane in some Romanian Carpathian crystalline formationsTschermaks Mineralogische und Petrographische Mitteilungen, 1969
- Simultaneous determination of water and carbon dioxide in rocks and mineralsThe Analyst, 1958
- The stilpnomelane group of mineralsMineralogical Magazine and Journal of the Mineralogical Society, 1938