The structures of the principal feldspars

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

Moderately accurate structure analyses have been completed for most of the "key" felspar structures-sanidine, orthoclase, microcline; low-temperature and hightemperature albites; celsian; anorthite. Their salient features are described and discussed, and applied to the consideration of the series of "mixed" K-Na, K-Ba and Na-Ca felspars. Some information is also available about the structures of oligoclase, andesine and bytownite, important members of the Na-Ca (plagioclase) series.

Certain important generalisations which emerge from these structural studies are summarised.

The paper also provides a basis for the detailed accounts, to be given by following contributors, of the maximum microcline structure, of the three-dimensional analysis of low al bite, of the peristerites, of transitional anorthite, and of order-disorder effects in felspars.