The relationship of orthopyroxene to pigeonite

Abstract

Interest in the orthopyroxene series is evidenced by the great number of publications on that subject which appeared in the literature. Correlations of the chemical composition and optical properties were attempted by Winchell (1923, 1933), Walls (1935), Henry (1935), and Hess and Phillips (1940). The nomenclature of the series was discussed by Winchell (1923), Alling (1936), and Hess and Phillips (1940). The obscure phenomena exhibited by certain orthopyroxenes in polarized light, attributed by some to twinning, by others to exsolution, was noted by a great many petrologists, of whom are mentioned here Lewis (1908), Holmes and Harwood (1928), Guimarães (1933), Scholtz (1936), Hess and Phillips (1938, 1940), Kuschke (1939), Wager and Deer (1939), Nel (1940), Walker (1940, 1943), Walker and Poldervaart (1940, 1941), Edwards (1942), Henry (1942), and Poldervaart (1944, 1946).