D4. PROCEEDINGS OF THE ROYAL SOCIETY OF QUEENSLAND. 
other rock showing this curious association has been described. 
Concerning this, Dr. J. 8. Flett writes as follows :—‘‘ Tour- 
maline-Albite Rocks.—In two places within this sheet (347) rocks 
have been found belonging to a class which has not hitherto 
been described. They consist of tourmaline and albite, and 
are undoubtedly altered states of the killas or clay slates, 
seeing that they retain the banding and slip-cleavage which 
the killas alone displays.”” The albite occurs as “a colourless 
mineral in the clear bands of the rock.’ Further, ‘it forms 
grains of very small size and very irregular shape, which 
seldom show twinning of any kind. ‘The tourmaline is in 
small prisms which have brown and bluish green colour.”’ § 
Dr. A. Harker, F.R.S., to whom a specimen of the Enoggera 
rock was sent, writes to the author concerning it, as follows :— 
** The tourmaline-albite rock is interesting, and is apparently 
a rare type. The only other occurrence known to me is on 
the border of the St. Austell granite, in Cornwall, and has 
been briefly described by Flett in the Survey Memoir (Geology 
of Bodwin and St. Austell). I collected and sliced this Cornish 
rock some years ago, when Benson and If visited the district. 
It differs somewhat from yours, the albite being in little clear 
untwinned granules, easily mistaken for quartz, and the little 
prisms of tourmaline having a more pronounced parallel 
arrangement.’ This communication from the eminent 
petrologist is especially important, since Dr. Harker alone has 
had the advantage of handling the specimens from both 
Cornwall and Queensland. 
The presence of tourmaline in localised patches (usually 
associated with quartz) in rocks intruded by a granite magma 
is, of course, quite a common phenomenon, and can in most 
cases be readily explained, but the presence of albite in such 
rocks is a matter which seems to admit of more than one 
explanation. The mineral may be original, it may be a product 
of metamorphism of pre-existing minerals, or it may have 
been introduced by the granite magma. 
With respect to the last possibility, the evidence is some- 
what conflicting; for, although petrologists were, as the 
result of a great weight of evidence, forced to the conclusion 
that a transfer of soda from the invading to the invaded mass 
8 Petrological Notes in ‘“* The Geology of Bodmin and St. Austell,” 
1909, p. 103. 
