Cation site-occupancies and infrared spectra for Na-Ca and alkali amphiboles in manganese ore deposits from Japan and India

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With the combination of Mossbauer spectroscopy and an electron probe microanalysis, the relationships between the cation site-occupancies and infrared spectra for Na-Ca and alkali amphiboies in manganese ore deposits from Japan and India have been investigated. The fractionation ratios of Na, Ca, and Mn in their M(4) site are closely related to the A-site alkali metal occupancy： for amphiboles nearly unoccupied with alkali metal at A site (0,00～0.25 Na＋K, per formula unit) Mn is strongly concentrated in the M(4) site ; in A-site panially occupied (0.25～0.75 p.f.u.) amphiboles Mn content becomes to decrease whereas the populations of Na and Ca become to be predominant ; and in A-site fulfilled (0.75～1.00p.f.u.) amphiboles Na and Ca are also predominant. The distribution of manganese in their M(1)・M(2)・M(3) sites increases with increasing the A-site alkali metal occupancy. A-site occupaneies estimated by means of the chemical analysis are roughly proportional to those values calculated from infrared OH stretching bands. The frequencies and intensities of almost all their infrared absorption bands are closely related to the A-site occupancies in these amphiboles.
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