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The pyroxenes of the alkaline igneous complexes of eastern Uganda

Published online by Cambridge University Press:  14 March 2018

Ruth C. Tyler
Affiliation:
62 Hallgarth St., Durham1
B. C. King
Affiliation:
62 Hallgarth St., Durham1

Summary

Chemical analyses, some optical data, and specific gravities are given for 57 pyroxenes from the alkaline rocks of Uganda. They are members of the diopside-hedenbergite-acmite series, the more diopsidic varieties occurring in rocks of the ijolite series and the more acmitic in syenites and carbonatites. TiO2 is highest in those pyroxenes from rocks that do not contain melanite. The refractive indices and specific gravities are controlled by the Fe2+/Mg ratio in the diopsidic pyroxenes and by the Fe3+ content in the acmitic members. Paragenesis is discussed briefly.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1967

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