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Published online by Cambridge University Press: 01 May 2009
Of the naturally occurring forms of (Mg, Fe) SiO3, only two are of any great petrological importance. Rhombic pyroxenes of the enstatite-hypersthene series are common in many igneous rocks and in the metamorphic derivatives of these and of sediments. Members of the anthophyllite group of rhombic amphiboles are of much more restricted occurrence, being practically confined to crystalline schists and metasomatic products. The stability relationships of these forms and of the rarer monoclinic clinoenstatite and kupfferite were originally investigated by Allen, Wright, and Clement. Enstatite was obtained by crystallizing a glass below 1100° C., and anthophyllite by very rapid cooling from a melt at about 1600° C. Some uncertainty still exists, but it is clear that at least under normal pressure clinoenstatite is the only stable form.
page 514 note 1 It seems desirable to apply the name kupfferite to the monoclinic form of amphibole, the end-member of the cummingtonite series, in accordance with the original usage by Kokscharow, and that followed by Hintze, Dana-Ford and others. The Carnegie Institute workers apply it to the magnesian end-member of the anthophyllite series.
page 514 note 2 A.J.S., 4, xxii, 1906 385–438.Google Scholar
page 514 note 3 Eitel, W., Wissenschaft. Forschungsber., Naturwiss. Reihe, 1925, xiii, 44Google Scholar; Phys. Chem. der Silikate, Leipzig, 1929, 290.Google Scholar
page 514 note 4 Min. Mag., iii, 1880, 21.Google Scholar
page 514 note 5 Q.J.G.S., lxxxiii, 1927, 642–4.Google Scholar
page 514 note 6 Compt. Rend., cii, 1886, 1332.Google Scholar
page 514 note 7 Op. cit., p. 21. This analysis is given as of anthophyllite, but since slides of his own material show considerable amounts of pyroxene, it may reasonably be assumed that no separation was carried out, and that the analysis is that of an anthophyllite-pyroxene rock.
page 514 note 8 Journ. Wash. Acad. Sci., x, 1920, 413.Google Scholar
page 516 note 1 Op. cit., p. 1332.
page 516 note 2 Phillips, F. Coles, op. cit., p. 642.Google Scholar
