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Published online by Cambridge University Press: 01 May 2009
In a recent paper Professor Shand put forward a pleafor the more careful consideration, in rock classification, of the saturated or unsaturated state of the constitnent minerals. The criterion of saturation which is assumed is the capability of co-existence with some form of free silica, as shown by the “observed facts of distribution”. By means of this criterion, the rock-forming minerals are divided into two groups—the saturated minerals and the unsaturated ones. The former group includes the felspars, amphiboles,pyroxenes, micas, and most of the so-called accessory minerals, as well as those of pneumatolytic origin; while the latter group comprises the felspathoids, olivine, the spinels, corundum, and the garnets (except spessartite, which is put into the first class). Rocks are divided into three classes, according as they are made up wholly of saturated minerals, partly of saturated and partly of unsaturated ones, or wholly of unsaturated ones.
page 319 note 1 “On Saturated and Unsaturated Rocks”: Geol. Mag., Dec. V, Vol. X, pp. 508–14, 1913.
page 319 note 2 Lehrbuch der Petrographie, Bd. i, p. 450, 1866.
page 319 note 3 Quant. Class, of Igneous Rocks, 1903, p. 123 et seq.
page 319 note 4 e.g. Iddings, Amer. Journ. Sci., ser. III, vol. xxx, pp. 58–60, 1885.
page 319 note 5 Iddings & Penfield, ibid., ser. III, vol. xl, pp. 75–8, 1890.
page 319 note 6 “Pitchstones of South Arran”: Trans. Geol. Soc. Glasgow, vol. xv, pp. 19–37, 1913.
page 320 note 1 Diller, Bull. U.S. Geol. Surv., 1891, No. 79, pp. 21–33.
page 320 note 2 Cf. Iddings, Bull. U.S. Geol. Surv., 1890, No. 66, pp. 20–32.
page 320 note 3 Since this was written, Bowen & Andersen (Am. Journ. Sci., ser. rv, xxxvii, pp. 487–500) have described experiments which show that on cooling a melt of the composition Mg O–Si O2, some forsterite separates out first and then the residual liquid crystallizes as a mixture of silica and clinoenstatite.
page 321 note 1 Cf. Washington, Journ. Geol., xv, pp. 257–79, 357–95, 1907.
page 321 note 2 Kurnakov & Konstantinov, Zeit. anorg. Chem., Iviii, pp. 12–22, 1908.
page 321 note 3 Fenner, “The Stability Relationsof the Silica Minerals”: Amer. Journ. Sci., ser. rv, xxxvi, pp. 331–84, 1913.
page 321 note 4 Fenner, loc. cit., p. 342.
page 322 note 1 Allen, , Wright, , & Clement, , Amer. Journ. Sci., ser. rv, xxii, pp. 385–438, 1906;CrossRefGoogle ScholarAllen, & White, ,Google Scholaribid.., ser. rv, xxvii, pp. 1–47, 1909; Doelter, Neues Jahrbuch, 1897, pt. i, pp. 1–26.
page 322 note 2 Cf., for example, Allport, Q.J.G.S., xxxv, pp. 637–42, 1879; Wyllie, and Scott, , Geol. Mag., Dec. V, Vol. X, pp. 499–508, 536–45, 1913.CrossRefGoogle Scholar
page 322 note 3 Teall, Q.J.G.S., xli, pp. 133–44, 1885; see also Harrington, Rec. of Progress. Geol. Surv. Canada, 1877–8, p. 21 G.
page 322 note 4 Wyllie & Scott, loc. eit.
page 322 note 5 Cf. Lacroix, Minéralogie de la France, i, pp. 668–9, 1895.
page 322 note 6 Q.J.G.S., lxv, pp. 100–1, 1909.
page 322 note 7 Tscher. Min. u. Pet. Mitt., xxiv, pp. 537–42, 1905.
page 322 note 8 Holland, Mem. Geol. Surv. India, xxviii, pp. 117–249, 1898.
page 322 note 9 Cf. Hezner, Tsoher. Min. u. Pet. Mitt., xxii, pp. 437–505, 1903, for origin of eclogites.
page 322 note 10 Rec. Geol. Surv. India, xlii, pp. 208–30, 1912; xliii, pp. 41–7, 1913.
page 323 note 1 Bourgeois, Annales Chim. Phys., ser. v, xxix, p. 458, 1883; Vogt, Mineralbildung in Schmelzmassen, 1892, pp. 186–8, etc.
page 323 note 2 Gorgeu, Annales Chim. Phys., ser. VI, iv, pp. 536–53, 1885.
page 323 note 3 Boeke, Zeit. Kryst. Min., liii, pp. 149–57, 1913.
page 323 note 4 Geol. Small Isles (Mem. Geol. Surv. Scotland), 1907, p. 91.
