with small included grains of plagioclase. Reddish-brown biotite is present to a minor extent as small xenoblastic flakes in both hornblendic and pyroxenic bands, but is concentrated in some areas to the almost complete exclusion of the other two minerals. The garnetiferous band contains about 90% of a clear, faintly-green garnet which, though frequently occurring as porphyroblasts up to 0.5 mm. in diameter, is usually in grains of about one-tenth that size; the porphyroblasts contain a few small inclusions of pyroxene and plagioclase, while the smaller grains of garnet are associated in a finely granoblastic aggregate with grains of calcite, pale-green pyroxene and acid plagioclase. Qualitative chemical tests upon the garnet prove that it is a lime-rich type containing a little manganese. The pyroxene has properties agreeing with those of a fairly pure diopside. Calcite is common along with albite (Ab94. An6) as small xenoblastic grains moulded against the pyroxene and garnet; in a few areas large pools of calcite and plagioclase, which are clear in their central portions, contain scattered granules of pyroxene and garnet towards their margins. Embedded in places in the calcite and along cracks in the garnet are very fine fibres and short prisms of a brownish-pink mineral referred to thulite. The fibres, which frequently mass together as small spherulites, have parallel extinction, refringence slightly higher than that of the ordinary ray in the calcite (about 1.7), low birefringence and very faint pleochroism in shades of brownish-pink. The abundance of calcite in this band. and the lime-rich varieties of pyroxene and garnet, suggest that the original rock was a calcareous band interbedded in the tuffs. The pyroxene-hornblende-biotite-albite-granulite is of interest on account of its uncommon mineralogical constitution. It is well established that in basic igneous rocks undergoing either thermal or regional metamorphism of low grade, pyroxenes are unstable, and that they appear as crystalloblastic minerals only at high grades (e.g. see Harker, 1932, pp. 108, 110, 284). The stable plagioclase in such rocks, when adjusted to high-grade conditions, is a basic variety, typically labradorite (e.g. see Harker, 1932, pp. 93, 284; Tilley, 1924, pp. 65, 66, etc.). The Greenhills granulite, essentially basaltic in composition, must have been metamorphosed at high grade, judging from its high content of crystalloblastic pyroxene and its completely recrystallised condition (all traces of original igneous texture having been obliterated). The plagioclase (albiteoligoclase) is, however, much less calcic than is usual in such rocks, and the same is true for two specimens of adjacent and interbedded granulite (Nos. 210, 211). This mineralogical indication of spilitic origin is confirmed by chemical analysis of the granulite from Greenhills (Table II). Further, field evidence suggests that the granulites in question belong to the same series as the tuffs described from the north-eastern flank of the range and shown by chemical analysis to be spilitic in composition. Thus, although the writer is unaware of any previous record of similar pyroxene-granulites containing albite or oligoclase in place of the usual labradorite, it seems clear in the present instance that the Greenhills pyroxene-granulites are high-grade equivalents of the low-grade spilitic tuffs further north-east,