Some Petrological Aspects of Order-Disorder in Feldspars

A. S. Marfunin
Institute of the Geology of Ore Deposits, Petrography, Mineralogy, and Geochemistry, Academy of Sciences of the USSR, Moscow.

Summary: The results are presented of some recent feldspar studies that relate the fundamental concepts of order-disorder series to petrological problems. New diagrams have been prepared with coordinates ‘optical properties-chemical composition-structural state’. From direct observations made on natural minerals some conclusions have been reached about the sequence in which the solid-state transformations of ordering, unmixing, and twinning occur in feldspars.

A study has been made of the geological distribution of different structural types of alkali feldspars in single intrusive bodies (Tertiary granite, Palaeozoic syenite, Pre-cambrian charnockite), in magmatic complexes, and in different complexes of the Ukrainian Shield and the Caucasus Geosynclinal Province.

Mineralogical Magazine; December 1962 v. 33; no. 259; p. 298-314; DOI: 10.1180/minmag.1962.033.259.04
© 1962, The Mineralogical Society
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