UNUSUAL TOURMALINE-ALRIT£ ROCK FROM ENOGGERA. 57 
tourmaline.” Teall points out that this is “ approximately 
equivalent to the tourmaline hornfels of Continental petro- 
graphers.”'® He also states that “‘ the term hornfels is used 
by many writers as a general name for the innermost zone 
in regions of contact metamorphism, and thus applied even 
to schistose and banded rocks.”?? 
A classic example of tourmaline “ schists,” in which the 
schistosity is the direct result of contact metamorphism, is 
that described from Cornwall by Allport in 1876,2! where the 
‘ original lamination of the fine sedimentary matter has been 
replaced by a distinct foliated texture.” He adds: ‘‘ It should 
be stated, however, that a decided foliation is restricted to 
the immediate vicinity of the granite.’ In describing the con- 
tact effects on the Mylor slates, Reid and Flett state: ‘‘ Close 
to the granite and within the zone into which granite veins 
extend the slates become much twisted, gnarled, and knotted, 
are often full of tourmaline, and the gaps between the twisted 
laminz have been filled up with streaks and lenticles of quartz 
of schorl rock or of chlorite.”’?? These authors also describe 
the formation of “ muscovite-tourmaline schist with quartz 
from phyllites by heated solutions from the invading granite.” 
It seems that the effect of contact metamorphism on such 
rocks as slates and schists may be either to obliterate the 
schistosity or to greatly accentuate it, and both these types of 
alteration can be observed about the edge of the Enoggera 
granite. Rosenbusch has described a “ tourmaline hornfels, 
schistose in structure,” composed of tourmaline, staurolite, 
white mica, and quartz from the clay slates of the Vosges, 
but he points out that in contact rocks in this area the schis- 
tose structure is exceptional, and that as the innermost zone 
is approached all schistosity vanishes from the rocks and 
they become massive in character. 
Means, in describing tourmaline-bearing quartz veins 
from Ontario,2* speaks of “‘ narrow bands of highly altered 
country rock embedded in quartz,’ and consisting of “a 
19 British Petrography, 1888, p. 386. 
20 British Petrography, 1888, p. 375. 
— SE OWS) (oii, Vell: Bost salve, (6. 
22 ““ The Geology of the Land’s End District,” p. 9. 
23 Quoted from Teall, op. cit., p. 375. 
24 Economic Geology, 1914, p. 129. 
