280 AUSTRALASIAN ANTARCTIC EXPEDITION. 



With the decrease in the percentage of felspar, the colour of the rock deepens, 

 and a dark-green type, like No. 599, is produced. It differs from Nos. 157, 257, and 522, 

 in possessing a massive structure. It has an increased percentage of chlorite, and 

 possesses relationships with the epidote-chlorite-schists of Group IV. Epidote is th e 

 most abundant mineral, and, together with the decrease in felspar, indicates a 

 transition towards the epidosites, the Epi division of Group IX, the lime silicate schists. 

 Chlorite is much more abundant than in previous specimens, and there is only a trace 

 of hornblende. Quartz is present, but subordinate in amount to the felspar. Both 

 quartz and felspar show cataclasis, and some crystals appear in polarised light as fine 

 granulitic aggregates. Ilmenite is present, and its association with sphene is another 

 point of resemblance with the amphibolite group. 



With the decrease of both chlorite and felspar, a massive green rock of 

 epidosite is produced. No. 255 is an example of this class, consisting chiefly of epidote. 

 The section has a uniformly yellowish-green colour, due to the epidote. Quartz is present 

 but very subordinate. A little pale hornblende exists as relic crystals, and a little 

 chlorite is intergrown with the epidote. Sphene, with associated magnetite, is an 

 abundant accessory mineral, and a little calcite is present. This rock is a member of 

 the Epi division of Group IX, the lime silicate rocks. 



V. DESCRIPTION OF PLATES. 



PLATE XL. 

 Fig. 1. No. 520, an amphibolite in which the hornblende shows a mottled appearance, 



due to the separation of blue hornblende from the green hornblende. Mag. 



35 diams. 



Fig. 2. Veins of lawsonite traversing a gabbro gneiss No. 515. Mag. 35 diams. 

 Fig. 3. Amphibolite No. 941, in which granulitic hornblende has developed from 



large crystals of hornblende. The nicols are crossed, and the large crystal 



which occupies most of the field is nearly in a position of extinction, while 



the granulitic hornblende appears light due to its bright polarisation colours. 



Mag. 35 diams. 

 Fig. 4. No. 169, in which a crystal of hornblende is partially altered to a mixture of 



calcite, epidote, and lawsonite. Mag. 35 diams. 



PLATE XLI. 



Fig. 1. No. 50, hornblende-plagioclase-gabbro gneiss. 

 Fig. 2. No. 339, garnet-hornblende-plagioclase-gabbro gneiss. 

 Fig. 3. No. 969, saussurite-gabbro gneiss with augen of saussurite. 

 Fig. 4. No. 721, segregation vein of hornblende, felspar and subordinate quartz in 

 amphibolite. 



[\Vith Two Plates.] 



Sydney: Alfred James Kent, Government Printer 1923. 



