274 AUSTRALASIAN ANTARCTIC EXPEDITION. 



EPI DIVISION. 



A larger development of chlorite occurs in specimen No. 229, which may be 

 called a chlorite-hornblende-schist. The formation of chlorite has been accompanied 

 by the development of a little epidote, and the separation of a little quartz. In places 

 the ends of the hornblende crystals are frayed out into needles embedded in quartz. 

 Some of the hornblende crystals show the effects of crushing, with an alteration toward 

 chlorite. Ilmenite is disseminated through the section, and there are occasional grains 

 of untwinned felspar. The marked development of chlorite is a feature associated 

 with the Epi division of this group, in which this rock has been included. 



Another specimen of hornblende-schist, No. 888, contains a curious plate of 

 chlorite, which is composed of layers of chlorite. In each layer the micaceous laminae 

 of chlorite are arranged more or less at right angles to the trend of the layer ; but the 

 laminae in adjoining layers are set at varying angles in one another. Both chlorite and 

 hornblende in this specimen possess a very pale green colour, being nearly colourless. 



A specimen that can be placed in this division is No. 916, a dense, dark green 

 pebble bearing glacial striae. It is a close relative of the epidote-chlorite-schists of 

 Group IV, but it is distinguished by its very subordinate amount of clear felspar. It 

 consists chiefly of epidote and chlorite. The iron, which has been discharged during 

 the conversion of biotite and hornblende into epidote and chlorite, is disseminated 

 throughout as numerous small particles of ilmenite. A little zoisite is associated with 

 the epidote. Sphene and apatite are not observed, but white mica is a minor constituent. 

 The rock is an epidote-chlorite-schist ; and, since chlorite is the more important 

 constituent, it is included in the family of chlorite schists. If epidote had been more 

 important, the rock would be related to the epidosites of the Epi division of Group 

 IX, the lime silicate gneisses. 



Specimen No. 931 is a fine grained, dark-green, schistose type with thin bands 

 of light green epidote. The percentage of felspar and quartz is very small, and even 

 less than in the preceding type No. 916. The main mass of the rock consists of epidote 

 and hornblende, chlorite being a very minor constituent. In addition to the more 

 important pale green hornblende, there is a clear colourless hornblende, and both 

 varieties are intergrown in one crystal. The colourless hornblende shows the brighter 

 polarisation colours and a slightly larger extinction angle. A colourless pyroxene is 

 present, partially altered to hornblende, and more prominent in some layers than 

 others. Granular epidote is abundant through the section, and has in part segregated 

 into layers. The small percentage of felspar and quartz is mostly confined to 

 these layers. Associated with the epidote crystals are a number of zoisite crystals, 

 possessing grey and ultra-blue polarisation colours. Sphene is an important accessory, 

 and forms thin strings of crystals in the layers of epidote. One corner of the section 

 is crossed by a narrow vein of serpentine. The rock is an epidote-hornblende-schist, 

 and the development of epidote, almost to the exclusion of chlorite, produces a 

 resemblance towards the epidosite family. 



