Halleflinta

Hälleflinta (a Swedish word meaning rock-flint) is a white, grey, yellow, greenish or pink fine-grained rock consisting of an intimate mixture of quartz and feldspar.

It is essentially metamorphic and occurs with gneisses, schists and granulites, especially in the Scandinavian peninsula, where it is regarded as being very characteristic of certain horizons.

[1] Of its original nature there is some doubt, but its chemical composition and the occasional presence of porphyritic crystals indicate that it has affinities to the fine-grained acid intrusive rocks.

In this group there may also have been placed metamorphosed acid tuffs and a certain number of adinoles (shales, contact altered by intrusions of diabase).

[1] Rocks very similar to the typical Swedish hälleflintas occur in Tirol, in Galicia and eastern Bohemia.