Observations on plagioclase aventurines from southern Norway

Forelesninger holdt ved Advanced Study Institute of Feldspar - Oslo 1962
Lectures held at Advanced Study Institute of Feldspar - Oslo 1962

It is with some pride that we admit that, even with the aid of modern experimental and diagnostic equipment, we cannot add anything new to the excellent treatise on aventurine feldspars given more than 45 years ago by the Norwegian State Geologist Olaf Andersen (1915). The information given in the present paper mainly serve to prove the correctness of the suggestions made by Andersen, which he had no possibility to prove himself simply because the standard of diagnostic equipment was not sufficient for this purpose at that time.

A venturine is no mineral name - it is a name of a yellowish to reddish schiller in minerals, it has been found in quartz, plagioclase, alkali feldspar, cordierite, cancrinite and carnallite. The aventurine effect in quartz and cordierite is mainly due to small flaky inclusions of mica, in feldspars, cancrinite and carnallite it is due to inclusions of hematite.