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Two new pyroxenes included in the system clinoenstatite, clinoferrosilite, diopside, and hedenbergite

Published online by Cambridge University Press:  14 March 2018

W. A. Deer  and
L. R. Wager
W. A. Deer
Affiliation:
Department of Geology, University of Manchester
L. R. Wager
Affiliation:
Department of Geology, University of Reading
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Extract

Two monoclinic pyroxenes from the Skaergaard Halvoen intrusion, Kangerdlugssuak, East Greenland, have been separated and analysed. They occur in a strongly differentiated gabbro complex which ranges from a hypersthene-olivine-gabbro at the base to a fayalite-quartz-gabbro of unique composition at the top. The differentiation has proceeded with a steady increase in iron and a corresponding decrease in magnesia, while the other major oxides remain relatively constant throughout. The clinopyroxenes in the lower horizons are in equilibrium with labradorite, normal olivine and hypersthene, and are fairly normal varieties as shown by the following optical properties:—

  1. (1) … α 1·672, β 1·678, γ 1·701, 2V 42°, γ: c 39°, sp. gr. 3·34.

  2. (2) … α 1·695, β 1·702, γ 1·722, 2V 43°, γ: c 41° sp. gr. 3·38.

Type
Research Article
Information
Mineralogical magazine and journal of the Mineralogical Society , Volume 25 , Issue 160 , March 1938 , pp. 15 - 22
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1938

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References

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