Nambulite, (Li, Na)Mn_4Si_5O_<14>(OH), in the Sausar Group of rocks in Central India

概要

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Manganese carbonate-silicate rocks in the Sausar Group, India are often traversed by pegmatite veins. Nambulite, a lithium- and sodium-bearing hydrous manganosilicate, is formed by the reaction of a hydrothermal solution with the host mineral, rhodonite. Despite the similarity of natronambulite and nambulite, the chemical composition shows a variation in the concentration of Na+ in the empirical formula: (Li0.94-0.60Na0.06-0.40)Σ1.00(Mn3.57-3.82Ca0.13-0.07Mg0.36-0.07Fe0.03-0.01)Σ3.96-3.86Si5.01-4.98O14(OH)1.00. This is the first report of the sodium-rich variety from India. Powder X-ray diffraction studies reveal the unit cell parameters of nambulite in the triclinic system as a =7.55 ± 0.06 Å, b = 11.77 ± 0.07 Å, c = 6.68 ± 0.04 Å, α = 91.3° ± 0.8°, β = 95.4° ± 0.5°, γ =107.2° ± 0.7° and V= 563 ± 6 Å3.
日本鉱物科学会の論文
2005-02-01