Feltspat IV. Forekomster i Akershus og Østfold øst for Glomma.

Abstract

In this publication, which is a sequel to Feltspat II and III by Olaf Andersen and Tom F.W. Barth, brief and exoteric descriptions and some information on production and history are given of about 180 individual feldspar, quartz, and mica deposits, all of them situated east of the river Glomma in south-eastern Norway. Particulars of purely geological or mineralogical interest are few; most of them are given as footnotes or in the preface, but the minerals of each deposit, exceot quartz, feldspar and mica, are listed. The deposits are cross cutting pegmatite dikes, with a northeastern strike and a steep dip. The dikes exhibit a marked zoning; moreover, they are remarkably free from rare minerals, the occurrences of which seems to be restricted almost entirely to the dikes near the Idefjord (Bohus) granite.