II. On Primary Analcite and Analcitization

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Abstract
Although in recent years a large number of rocks containing analcite have been described, there is still some difference of opinion regarding the origin of the mineral. It had often been observed in igneous rocks, but was always considered to be secondary until, in 1890, Lindgren ( cf. 1893, p. 289) concluded that it must be primary in some analcite-basalts. These rocks contained phenocrysts of olivine, augite and analcite in a mesostasis of the two latter minerals. The analcite was separated and analyzed and the composition found to agree with NaAlSi2O6.H2O. In the same year, Hunter and Rosenbusch (1890, p. 455) determined the chemical composition of the “glassy” base of the monchiquites, but Pirsson (1896, pp. 682-3) was the first to identify it as analcite. He considered the mineral in this rock to be primary, as also did Cross (1897, p. 690) in a phonolite, Washington (1898, p. 187) in a tinguaite, and Coleman (1899, p. 436) in heronite. This view, to which most of the British writers who have recently described analcite-bearing rocks have subscribed ( cf. Campbell and Stenhouse, 1908, p. 128, and Flett, 1910, pp. 295-6), has been upheld particularly by Tyrrell (1912, p. 71) in the case of the Permo-Carboniferous rocks of the West of Scotland. Hibsch (1910, p. 427) is of the same opinion with regard to the mineral in nephelite-basalt and monchiquite from Bohemia. Most of the continental writers, however, postulate a secondary origin. Thus Brögger (1890, pp. 223-32) and Ussing (1894, pp. 118, 135) considered This 250-word extract was created in the absence of an abstract

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