Study of Minerals from the Pegmatites of the Nellore Mica-Belt, Andhra Pradesh, India Part III

Study of Minerals from the Pegmatites of the Nellore Mica-Belt, Andhra Pradesh, India Part III—Biotite

V. R. R. M. Babu

Department of Geology, Andhra University, Waltair

Summary: The biotites in the pegmatites are Fe²⁺ type. X-ray analyses indicated that they are 1M or 3T polymorphs. In the colour of the biotite iron plays an important role. From the Fe/(Fe+Mg) ratios, the analysed biotites are assumed to have crystallized between 760 and 500 °C.

Mineralogical Magazine; September 1969 v. 37; no. 287; p. 391-393; DOI: 10.1180/minmag.1969.037.287.12
© 1969, The Mineralogical Society
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