Citation: Thompson, R. M.; Downs, R. T. (2004). Model pyroxenes II: Structural variation as a function of tetrahedral rotation model orthoenstatite after Hugh-Jones and Angel (1994) with O3A-O3A-O3A angle = 158.7, O3B-O3B-O3B angle = 139.0, and model oxygen radius = 1.302. American Mineralogist, 89, pp. 614-628.