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III.—On a Hornblende-Picrite from the Zmutthal (Canton Valais)

Published online by Cambridge University Press:  01 May 2009

Catherine A. Raisin
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Extract

While staying at Zermatt in the summer of 1894, I searched among the boulders from the Zmutt glacier for several types of rock, which, as suggested to me by Professor Bonney, were likely to occur. I am further indebted to him for kindly giving me his help and opinion on several questions while I was writing this note.

Type
Original Articles
Information
Geological Magazine , Volume 4 , Issue 5 , May 1897 , pp. 202 - 205
Copyright
Copyright © Cambridge University Press 1897

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References

page 203 note 1 It is usually not dichroic, exhibits well-marked cleavage planes, and the high extinction angle of augite.

page 203 note 2 As described by Professor Bonney, “On the so-called Diorite of Little Knott (Cumberland), with further remarks on the Occurrence of Picrites in Wales”: Q.J.G.S. 1885, vol. xli, p. 520.Google Scholar

page 203 note 3 The enstatite has close parallel cleavages which almost seem to form a repeated twinning, but this (examined with a high power) is seen to be an effect of a large number of elongated vesicular-looking enclosures, which are probably negative crystals formed along gliding planes. Cf. Prof. Judd, Q.J.G.S. 1885, vol. xli, p. 354.Google Scholar

page 203 note 4 This may possibly indicate a local deficiency of lime in the magma, a thing not surprising, as peridotites are often ill-mixed rocks.

page 204 note 1 “On Bastite Serpentine and Troktolite in Aberdeenshire”: Geol. Mag. 1885, Decade III, Vol. II, p. 444, note.Google Scholar

page 204 note 3 Trans. Royal Irish Acad., vol. xxix, pp. 462–3.Google Scholar

page 204 note 3 Q.J.G.S. 1886, vol. xlii, pp. 94–3, pl. vii, fig. 7.Google Scholar

page 204 note 4 Q.J.G.S. 1888, vol. xliv, p. 455.Google Scholar

page 204 note 5 In my specimen of the Penarfynydd picrite, which I collected in 1885, the olivine contains, sometimes at the edge, clusters of needle-shaped structures either parallel or radiating in a stellate form, the needles in both cases suggesting minute fissures starting from a centre. At places the parallel bundles seem to be connected with a fibrous chrysotile development

page 204 note 6 Bonney, T. G., “On some specimens of Gabbro from the Pennine Alps”: Min. Mag., 04, 1878.Google Scholar Bonney, T. G., “Petrological Notes on the Euphotide or Saussurite-Smaragdite Gabbro of the Saasthal”: Phil. Mag. 1892, vol. xxxiii, ser. 5, p. 237.CrossRefGoogle Scholar Schäfer, R. W., Tschermak Min. and Petr. Mitth. Wien, Bd. xv, Heft. 1 and 2, 1895, p. 132.Google Scholar

page 205 note 1 Cf. Bonney, T. G. in Geol. Mag. 1880, p. 208, A.Ilarker, loc. cit.Google Scholar