AMFHIBOLITES AND RELATED ROCKS STIKLNVKLL. 267 



tered grains of epidote, chlorite, and muscovite occur in the felspar areas. In 

 this case, the features of the Epi division include the presence of epidote and the 

 cataclastic structures, in addition to the presence of saussurite and chlorite. 



Specimen No. 828 is a similar porphyroblastic ohlorite-amphibolite, but the 



r;it;icl:isis and mortar structure are much more pronounced. The margins of the 

 hornblende crystals have been crushed and converted into chloritic selvages. The 

 porphyroblasts of felspar are elongated along the schistose planes, and are surrounded 

 by chlorite and finely -gran ulitic quartz and felspar. This rock also contains occasional 

 large crystals of allanite. 



Specimen No. 961 is an Epi-amphibolite, in which the hornblende crystals display 

 a remarkable mortar structure. It is a highly schistose rock, containing a a larger 

 percentage of hornblende than the typical amphibolite. The fracturing and grinding 

 of the fragments of hornblende have produced zones and films of green chlorite around 

 islands of unaltered hornblende. A blunt hornblende crystal often assumes a lenticular 

 shape where the chloritic brash is drawn out along the schistosity. The clear mineral 

 is an acid plagioclase, frequently drawn out into lenticular shapes along the schistosity. 

 Some crystals show a mortar structure, while others have been reduced to finely- 

 pulverised aggregates. 



Specimen No. 233 is a chlorite-amphibolite, in which the alteration of hornblende 

 into chlorite has been extensive. It contains large pale green to colourless crystals of 

 hornblende, which are all partly converted into chlorite. The greater proportion of 

 tho chlorite, which is the most abundant mineral in the rock, has been formed in this 

 way. A subordinate quantity of chlorite appears to be pseudomorphous after biotite. 

 The felspar is cloudy, and occurs in granular crystals. Though mostly untwinned, 

 it is probably an acid plagioclase. In a vein that traverses the section, it has 

 r.'i r vstallised as clear albite. Ilmenite, granular sphene, and apatite are distributed 

 freely through the rock. Epidote is a minor constituent, except in the neighbourhood 

 of the vein, where it is associated with chlorite and clear albite. 



Specimen No. 210 is an interesting relative of the epidote-biotite-schist, No. 153, 

 which occurs as an altered dyke rock at Cape Denison 1 . Its structure is more massive 

 and less schistose than No. 153. The biotite of No. 153 is replaced by a green pleochroic 

 chlorite, and epidote crystals are more numerous than in No. 153. The clear felspar 

 is an acid plagioclase, and no basic felspar is present. Sphene and magnetite (or 

 ilmenite) are important minor constituents, and are associated together in the same 

 manner as in the typical amphibolites. Apatite is an accessory mineral, and there 

 are occasional grains of calcite. The amount of felspar appears to be less in this rock 

 than in No. 153, tending to make this specimen a typical member of the family of 

 epidote-chlorite-schists. 



An interesting specimen is the lawsonite-chlorite-schist, No. 936. It is one of 

 the few specimens from this region which shows surface weathering, being covered 

 with a brown iron-stained skin. A brown colour also appears on the fractured surface, 



i,t,.-J -I; dp cit.,p. 3U. 



