This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1908 edition. Excerpt: ...quartz largely predominates over mica, both macroscopically and microscopically, and schistosity is not so perfectly developed as in the biotite-schists. Schists of this character especially characterize the upper schists above the horizon of the Pounamu Formation. They are hard and tough, whilst lamination-planes are rather poorly developed, so that the rock does not split well. The silicified feldspars occasionally seen in these schists may have originally. developed under the influence of the Pounamu intrusions, but more probably represent primary grains. The actinolite-biotite-quartz-schists have a very limited extension. In them idiomorphic actinolite is developed in some abundance, and quartz largely exceeds biotite in quantity. They ought perhaps to be referred to group (cl), but are mentioned here because in part at least they are not known to be connected with the Pounamu Formation. Epidote is probably always present. The chloritic quartz-schists are not of frequent occurrence. They consist of quartz foliae, with more or less chlorite. Those with a high percentage of chlorite may be referred ltgroup (d). 6'--Mikonui. (b.) Quartz-schists.--Certain light-coloured bands in the middle and upper schists, more especially near the horizon of the Pounamu Formation, which consist almost entirely of quartz, and have apparently been silicified by the agency of hydrothermal solutions, may be described under this heading. They graduate into quartz-mica-schists. (0.) Ph_z/ll-ites.--The distinction between the biotite-schists and the phyllites is a very small one, consisting mainly in a finer micro-structure and a less degree of metamorphism. The phyllites found in the Mikonui Subdivision may be placed in two classes. One of these forms a belt...