The heavier accessory minerals in the granites of Scotland

Abstract

Early in 1915 a trial separation of the heavy minerals from a specimen of granite from one of the apophyses of the Benrinnes mass disclosed the presence of monazite, zircon, anatase, garnet, etc. Quite a number of crystals of monazite, some of them of considerable size, were found in the residue, and as only two occurrences of that mineral,1 so far as known, had previously been recorded from Scottish rocks, the result was considered of such importance as to suggest a general inquiry into the distribution of that and other heavy accessory minerals in the granites of Scotland. Since then about 200 specimens of granite and kindred rocks have been examined from as many different localities throughout Scotland and the results are given below. Apart from the wide distribution of monazite disclosed by the investigation, many other interesting facts have come to light, both as regards the distribution and association of other heavy minerals in the granites examined; and though monazite was the primary object of search, it was soon discovered that a number of other interesting facts, regarding the character, association and distribution of such commonly occurring minerals as zircon, apatite, garnet, etc., were gradually being accumulated. Some of the points in regard to the different minerals will now be briefly discussed. 1. Monazite. —The mineral has been found in about half of the number of specimens of granite from different localities that have been examined—in 85 out of 178. The mineral is found to occur in varying but always