UNUSUAL TOURMALINE-ALBITE ROCK FROM ENOGGERA. 49 
N.N.W. direction, which is the normal strike of the Brisbane 
Schists, and is, further, the most important trend line in the 
Brisbane area. This agreement in direction may, however, 
be merely coincidental, for the schists twenty yards further 
from the contact strike E.N.E. (i.e., roughly parallel with 
the edge of the granite laccolite at this point), and dip to the 
N.N.W., while between the tourmaline-albite rock and the 
contact the strike is very erratic. 
The appearance of the rock in the field s very beautiful 
and striking, being black in colour with numerous irregular 
sinuous and contorted veins of a light-coloured material 
standing out in marked relief. A few feet away on either 
side an identical structure can be seen where numerous 
tortuous veins of quartz are threaded through the normal 
mica schists. The field evidence leaves no doubt that, how- 
ever the mineralogical nature of the tourmaline-albite rock 
be explained, the schistose structure is that of the Brisbane 
Schists themselves. 
Nearer the granite and almost on the contact is a large 
body of massive schorl rock composed almost entirely of 
tourmaline identical with that in the tourmaline-albite rock 
but in which only traces of the schistosity remain. These 
traces sometimes take the shape of numerous irregular roughly 
parallel but empty veins. This rock contains, in addition, 
cavities which are partly or almost completely filled with 
well-shaped quartz crystals and an occasional crystal of pyrites. 
Small patches of tourmaline are also found in the schist over 
fifty yards from the contact. 
These tourmaline rocks cannot be considered as in any 
way representative of the contact effects of the Enoggera 
Granite on the schists.* The Brisbane Schists outside the con- 
tact zone are in this locality a series of schistose and phyllitic 
rocks, consisting for the most part of mica, through which 
run numerous irregular veins of quartz, which follow the plica- 
tions and thus emphasize the schistose character of the rock. 
- The normal effect of the intrusion of the granite at this point 
is to produce in these schists a recrystallization of both mica 
and quartz, but no new minerals seem to have been added. 
* See Richards, ‘‘ A Study of the Brisbane Schists,’’ Inst. of En 
gineers, Brisbane Divn., June 1922, p. 5. 
3 See Bryan, 1914, op. cit., p. 152. 
R.S.—E 
