"Schists composed essentially of biotite and sphene have been found in many localities in the psammitic groups of the Moine series in Ardnamurchan. From petrographic and chemical evidence it is concluded that they were heavy mineral bands, composed of sphene and iron oxides with a matrix which was partly pelitic and partly quartzo-feldspathic. This postulated original composition may have been produced by sedimentary slumping, for which field evidence is available. The unusual chemical composition was probably accentuated at higher grades of metamorphism by metamorphic segregation, particularly a loss of soda or of albite into the surrounding arkoses."

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