Chemical data on a silica-poor argillaceous hornfels and its constituent minerals

Abstract

The hornfels discussed here was collected from Sparcraigs, near Whitecairns, eight miles to the north of Aberdeen, very close to the eastern contact of the basic igneous intrusion of Belhelvie. The Highland Schists of the district are very poorly exposed, but at this locality there are a few small isolated outcrops of high-grade hornfels, nearly all silica-poor types, with garnet, spinel, hypersthene, cordierite, plagioclase, and biotite as their chief mineral constituents. The actual contact is obscured, but the igneous rock, an olivine-gabbro, is exposed at about twenty yards from the hornfels.