NOTES ON ANTARCTIC ROCKS. 485 
augite. The flow structure is distinct, and the cavities and amyg- 
daloids are irregularly elongated parallel to its direction. These 
amygdaloids consist of a very irregular layer of brownish doubly- 
refracting material which fuses easily and gelatinizes easily with 
HCl even in the cold, and is most probably natrolite. 
The portions inside this layer are generally filled with colourless 
sectors of material which exhibits faint anomalous double-retrac- 
tion, and may probably be analcime. In some of the larger ones 
the centre is occupied by calcite surrounded by analcime which is 
again surrounded irregularly by natrolite. The natrolite exists 
in minute fan-shaped aggregates. 
Augite Andesite, (No. 12). 
Rock brownish in colour, considerably decomposed and porous. 
Small red grains indicate oxidation of magnetite crystals, and the 
general brownish tone due to oxidation of magnetite dust. There 
is not much actual staining of other constituents. Under the 
microscope appears to be an andesite of fine texture. 
The base consists of felspar microlites, a great number of 
smaller prisms and grains of yellow augite and magnetite (mostly 
converted to reddish oxides), and a fair amount of granular inter- 
sertal glass, almost colourless ond containing highly refracting 
globulites. There are some porphyritic crystals of brownish augite 
the outer shells of which are of a strong yellow colour similar to 
that of the small augites in the base. This is probably due to 
oxidation of the FeO. There are some dark patches in the base, 
some with regular outlines, which may represent the debris of 
another constituent, possibly a hornblende. 
Basalt, (Nos. 1 and 2). 
These are specimens of a fine, dark, compact basalt, with a few 
porphyritic crystals of black augite. Sp. gr. 2°82, 2°86. 
In section, flow structure is apparent from the parallel arrange 
ment of the sniall lath-shaped felspars, The texture is micro- 
“rystalline with a certain amount of intersertal glass of a brownish 
