An anorthite-epidote-garnet-hornfels from Namaqualand, South Africa
The present communication deals with a calc-silicate hornfels of uncommon mineralogical and chemical composition. It may be tentatively referred to the deep-seated metamorphism of a marl, and on account of the shortage of analytical data pertaining to metamorphosed sediments of the calcareo-argillaceous type, a detailed investigation of a variety of this group seems justified.Intercalated bands of anorthite-epidote-garnet-hornfels bordered bilaterally by pyroxene-bearing gneisses occur on the farms Zandfontein, Pella, and Klein Pella in the north-eastern part of the division of Namaqualand, South Africa (cf. geological map), On Klein Pella small exposures also extend intermittingly for approximately 1·5 miles due WNW.-ESE. of the amphibolite koppie situated on the northern boundary of the farm area. The bands exhibit a gentle pinch and swell structure with maximum widths of 15 to 41 inches, and the contact with the host rock is commonly marked by an epidotic fringe ¾ inch in thickness. In some cases the anorthite-epidote-garnet-rock is penetrated by parallel lenticles of pure quartz which may attain maximum breadths of 0·8 inch.