Art. LXXVIII.—Analyses of a Rock Specimen from New Zealand, showing the Junction between Granite and Slate.

By Archibald Liversidge, Professor of Geology and Mineralogy in the University of Sydney. Communicated by Professor Hutton.

[Read before the Otago Institute, 8th November, 1877.]

I Am indebted to the kindness of Capt. Hutton, F.G.S., Director of the Museum, Dunedin, for an opportunity to examine this most interesting specimen; although the dimensions of the specimen were originally only about one and a-half inches by one and three-quarters, and perhaps one inch in thickness, yet one-half of the specimen consisted of a fine-grained greenish grey-coloured slate, while the remaining portion was made up of a nearly white granite, possessing well-defined characteristics; the crystals of orthoclase felspar are fairly well-defined and exhibit comparatively large cleavage planes; the mica and quartz are also distinctly developed; even in so small a fragment the granite does not merge so insensibly into the slate as we might naturally expect, but the two are joined along a comparatively well-defined line of junction.

The following analytical results, which are each the mean of two analyses, show the differences in the chemical composition between the granite and slate portions of the specimen.

[The section below cannot be correctly rendered as it contains complex formatting. See the image of the page for a more accurate rendering.]