The Topaz-bearing Rocks of Gunong Bakau (Federated Malay States)

Publisher Website
Google Scholar
Abstract
I. Introduction. Igneous rocks with topaz as a constituent are well known, and it is unnecessary to give in detail the literature dealing with them. The best known are those in which the topaz is associated with cassiterite, and in such cases it is generally believed that the topaz has been formed by the tin-bearing media acting on felspar, converting part of the silicate of alumina into fluoride of alumina. The object of this paper, however, is to describe some clear sections in the Federated Malay States where two topaz-bearing rocks, both carrying cassiterite, are shown to have been intruded into porphyritic granite, and where the evidence is conclusive that both topaz and cassiterite are not alteration-products of previously formed minerals, but crystallized from the molten rock as topaz and cassiterite. Gunong Bakau (‘Gunong’ is the Malay equivalent for mountain) is a mountain 4426 feet high, situated in the centre of the Main Range of the Peninsula, on the boundary between the two States, Selangor and Pahang. The name will not be found on any published map, but it will suffice to say that, in the sketch-map accompanying my paper on the ‘Geological History of the Malay Peninsula’, its position is near the source of the River Selangor, at the boundary of the State of that name. The sketch-map accompanying the present paper (fig. 1, p. 364) gives some ideas of the surroundings of the mountain. On the west are the sources of the Rivers Kajang, Bakau, and Luit; on

This publication has 0 references indexed in Scilit: