NOTES ON ANTARCTIC ROCKS. 479 
places there are thin films of what is probably micaceous hematite 
making the olivine a brilliant transparent red. 
In many of the crystals the enclosed iron oxides have been 
attached and converted into opaque red hematite, so that the 
whole crystal appears of an opaque red by reflected light. The | 
larger crystals of magnetite have suffered in the same way, and 
’ the opaque red dust has spread over much of the ground-mass. 
Limburgite (No. 9). 
In the mass this rock is of a dark grey colour, compact with 
minute irregular cavities, and shows phenocrysts of augite and 
olivine. Sp. gr. 2-94 
It has very much the appearance of an ordinary olivine basalt. 
On microscopic examination, however, felspar was found to be 
entirely absent. Porphyritic augjtes and olivines are abundant ; 
they are clear and fresh, and show crystal boundaries. These 
augites are yellowish to pinkish-brown in colour, generally zoned 
and frequently twinned. Then we have a large crop of much 
smaller augites with a few small olivines, and finally there is a 
base of fine granular augite and greyish to brown intersertal glass 
dusted over with granules of magnetite. (Plate 15, fig. 3.) 
The colour of the glass varies in patches; in places it seems 
almost entirely absent, and elsewhere we find it in brown angular 
petebes filling the spaces between the second generation of augites. 
This glass is perfectly isotropic, but contains a dust of dark 
particles, Throughout the mass there are little irregular cavities 
which would appear to be contraction rifts consequent on crystal- 
: tion. Into these the augites of the second generation project 
with very good crystal boundaries. These cavities are filled with 
a colourless isotropic mineral with a few needle-like inclusions. 
is most probably analcime. ‘Treated micro-chemically with 
HCl it is decomposed, yielding a good crop of NaCl crystals and 
gelatinous SiO,. The separated silica is richly stained by 
malakite green, 
