Contribution to the Study of Ore Minerals in Some Igneous Rocks from Assynt

E. F. Stumpfl
University College, London, W.C. 1

Summary: The parageneses of opaque minerals in three Assynt rocks are described. A biotite-diorite dyke-rock of Lewisian age is characterized by a primary igneous assemblage of Fe-Ti oxides, pyrrhotine, and pentlandite. Effects of metamorphism are recognized, particularly in the oxidation of ilmenite in a Lewisian epidiorite dyke-rock. Cromaltite contains a primary assemblage of oxide minerals together with a later hydrothermal sulphide assemblage. Evidence from the opaque minerals cannot be reconciled with a theory of limestone assimilation. The correlation of the distribution of Co, Ni, and Cu in the rocks with the opaque minerals present is considered.

Mineralogical Magazine; June 1961 v. 32; no. 253; p. 767-777; DOI: 10.1180/minmag.1961.032.253.03
© 1961, The Mineralogical Society
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