Tinguaites and Camptonites from the Vicinity of Haast Pass. By F. J. Turner, Otago University. [Read before the Otago Institute, 14th April, 1931; received by Editor, 20th April, 1931; issued separately, 31st March, 1932.] Contents. Introduction. Petrography: (1) Tinguaites. (2) Camptonites. Mutual Relationship of Tinguaites and Camptonites. Course of Crystallisation of the Parent Magma. Correlation and Age. Acknowledgment and Thanks. Literature Cited. Introduction. The rocks described in this paper were collected early in 1930 from boulders in the beds of streams on either side of the Main Divide, in the vicinity of Haast Pass, on the boundary between North-west Otago and South Westland. On the Otago side of the divide, the boulders in question occur in the bed of the Makarora River for some distance below its junction with the Fish, as well as in the latter stream itself. At the point where the Makarora joins the Fish, it emerges from a precipitous, impassable canyon, so that it was not possible to ascertain whether boulders of the same type are to be found in the Makarora, upstream from the confluence. On the Westland side of the pass, igneous rocks are not represented among the boulders in the upper part of the Haast; but they were found to be plentiful in the bed of a small stream which enters the Haast from the west, about one mile below its junction with the Burke. Thus, although these rocks were never actually observed in situ, it is safe to assume that their source lies in the wild and unexplored ranges that stretch northward from the headwaters of the Fish, across the Burke, towards the junction of the Haast and the Lands-borough. The whole of this region is composed of a varied assemblage of mica-, chlorite-, and epidote-schists, which are continuous with the schists of Central Otago further south-east. The igneous rocks in question must therefore occur as dykes invading this schist formation.