56 PROCEEDINGS OF THE ROYAL SOCIETY OF QUEENSLAND. 
tourmalinised states of these hornstones.’’ Further, he writes 
that the specimens “show that albite is more resistant 
to pneumatolytic emanations than mica, as all the mica has 
disappeared, and this is in accordance with the frequency of 
albite in the china stones and kaolinised granites.’’!” 
One cannot assume in the present problem the presence 
of bands of albite in the unaltered schists, felspars in this rock 
being conspicuous by their absence, and must conclude that 
the albite is the result of contact metamorphism, and has 
either been formed by the recrystallization of the minerals 
already present in the rock or that it has been introduced from 
the granite magma just as the tourmaline was. The chemical 
evidence, such as it is, favours the former view, but it were 
safer to disregard this evidence altogether, for the analysis on 
which it is based is that of a sample of Brisbane Schist some 
miles distant. The field evidence and structure of the rock 
are decidedly in favour of the latter alternative; and they 
suggest, further, that the tourmaline aibite rock was formed 
in two stages, which, however, may have followed each other 
very closely. The first stage was the tourmalinisation of the 
‘micaceous part of the schist and the expulsion of the excess 
silica together with that of the quartz veins. This silica was 
subsequently redeposited in druses, such as are found in the 
neighbouring massive tourmaline rock which represents a part 
of the schist which was affected by this first stage only. 
The second stage saw the deposition of albite from hot 
aqueous solutions along the planes vacated by the quartz. 
(B) STRUCTURAL. 
The writer has found a number of descriptions, some of 
them illustrated by plates and figures, of tourmaline contact 
rocks, with structures very closely resembling that of the 
Enoggera rock. In some of these cases the schistose structure 
seems to be independent of, and in other cases the direct 
result of, the intrusion of the granite. Dr. Bonney!® has 
urged that foliated rocks of the latter type should not be termed. 
“ schists,” and agrees with Sir A. Geikie in the suggested 
revival of Dr. Boase’s old name “ cornubianite,’’ but has re- 
defined it as “essentially consisting of quartz, mica, and 
17 Op. cit., 1909, p. 103. 
18 Op. cit. Note to p. 104. 
