Page 306 note 3
Kunitz, W., Neues Jahrb. Min., 1924, Beihlge-Band 50, pp. 365–413
Google Scholar. [Min. Abstr., vol. 2, p. 424.] This valuable paper was read at the annual meeting of the German Mineralogical Society in 1922, and a preliminary abstract was published in Zeits. Krist., 1923, vol. 57, pp. 559-561. The details of the 32 new analyses were published while the present paper was in manuscript. The analyses, recalculated to SiO2 = 600, have been included in the present tables, and they fully confirm the earlier data. In many important respects the formulae assigned by Kunitz are in agreement with those here given. As regards the RO oxides, however, that author denies on ‘valency-thcoretical’ grounds that RO can replace R2O3 (p. 389) ; the phengites are explained as resulting from accidental inclusions (p. 378); and even the ferric oxide in lepidomelane is attributed to secondary alteration by reversible reaction between FeO and water (p. 389). Nevertheless it is recognized that lepidolite can be derived from muscovite by substituting Lifo for Al2O3 ; but phlogopite is derived from muscovite by putting 6RO in place of 2Al2O3 (p. 396) ; and the author concludes that without synthetic experiments a complete explanation of the valency difference between Li and A1 cannot be obtained. An attempt is made to deal with the question by means of complex groups such as [2 Li, Si], called ‘Le’, thus the lithia micas are written KH2Al2Le[SiO4]3 ; a formula which does not accord with the constant ratio K2O:6SiO2. The use of basic alumina radicles does not seem to have been considered, although early in the paper a reference is made to topaz. (See note on p. 318.)
