bytownite


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bytownite

[′bī·tau̇‚nīt]
(mineralogy)
A plagioclase feldspar with a composition ranging from Ab30 An70 to Ab10 An90, where Ab = NaAlSi3O8 and An = CaAl2Si2O8; occurs in basic and ultrabasic igneous rock.
References in periodicals archive ?
The core composition for all three types of crystals, as determined mainly by extinction angle methods, is bytownite for units A, C, E and G; labradorite for unit B and oligoclase for unit D.
Unit A is the most abundantly porphyritic basalt unit and its resultingly high content of bytownite is reflected in its high [A1.
In vogesite its composition ranges from andesine to bytownite, and minor albite occurs in the groundmass of monchiquite (Lindgren and Ransome, 1906; Loughlin and Koschmann, 1935; Thompson, 1992).