THE METAMORPHIC ROCKS OF ADELIE LAND 8T1LL\VELL. 213 



Fig. 3. The garnet rim around the biotite is broken by the development of a spray 

 of secondary biotite which opens out into the usual vermicular intergrowths of felspar, 

 but these are not visible in ordinary light. A certain amount of the secondary biotite 

 also appears on the outside of the garnet rim. Hypersthene felspar gneiss, No. 785 (2), 

 Cape Pigeon Rocks. Mag. 35 diam. 



Fig. 4. A flake of basal biotite is surrounded by a rim of younger biotite and quartz. 

 Hypersthene felspar gneiss, No. 979 (2), Stillwell Island. Mag. 45 diam. 



Fig. 5. Plagioclase pyroxene gneiss, No. 773, Cape Gray, showing chiefly a fine- 

 grained aggregate of pyroxene and felspar with scattered ilmenite. The outlines of 

 the felspar laths of the primary dolerite can be plainly detected. The rock has the same 

 percentage mineral composition as No. 794 (Plate IV., fig. 1). Mag. 35 diam. 



Fig. 6. The same field as Fig. 5 in polarised light. The primary felspar laths are 

 converted into granulitic aggregates of secondary felspar. Mag. 35 diam. 



PLATE VII. 



Fig. 1 . Hornblende plagioclase pyroxene gneiss, No. 766, Cape Gray. The schistose 

 character is seen, and the dark hornblende is distinct from the paler pyroxene. A plate 

 of relic pyroxene is seen partly altered to the fine granulitic aggregate of secondary 

 pyroxene and hornblende. Mag. 35 diam. 



Fig. 2. Garnet plagioclase pyroxene gneiss, No. 935, Stillwell Island. The field 

 is occupied by a large crystal of relic pyroxene which is darkened by numerous minute 

 crystals of ilmenite. On the left and extreme right the relic pyroxene is replaced by 

 granulitic aggregates of clear secondary pyroxene with the partial coalescence of the 

 minute ilmenites. The relic pyroxene is also partly replaced by granulitic aggregates 

 of hornblende which surround an ilmenite nucleus. Mag. 45 diam. 



Fig. 3. Garnet amphibolite, No. 799, Garnet Point. Note the manner in which 

 the garnet crystal is set in a felspar base. Mag. 35 diam. 



Fig. 4. Amphibolite, No. 781, Garnet Point. This is the amphibolite which 

 junctions the cyanite biotite gneiss in Plate III., figs. 1 and 2. Mag. 35 diam. 



Fig. 5. Plagioclase pyroxene gneiss, No. 951, Stillwell Island. The crystals of 

 biotite and pyroxene are surrounded by a diablastic intergrowth of pyroxene and felspar. 

 This pyroxene is partly granular and partly vermicular, and is interpreted as the first 

 stage in the production of garnet. Mag. 35 diam. 



Fig. 6. Hornblende plagioclase pyroxene gneiss, No. 942, Stillwell Island. The 

 centre is a roughly circular area of diablastic pyroxene and felspar which is partly 

 surrounded by hornblende and biotite. In the lower part of the photograph the larger 

 granular pyroxene is seen. Mag. 35 diam. 



