LARGE TIN, s EI 9 RO 
ELAR Pee «pet eee Y RES SSeS o TS n 
ue ro ai LER ccu oe E 
j 
x 
3 
PES 
Se 
157 
genetically related to wa mu The series comprises 
microcline aplites and mber of albite pegmatites 
(albitites), viz., quartz a dn albitites. These rocks 
traverse the granite in the form of dykes, and also as irregular 
masses, and Ri been the later stages of the crystallization 
of the ‘granitic ma 
The microcline Agit intrusive mass is the home of the 
quartz-tourmaline nodules now under discussion. This aplite, 
known as the ‘‘Pink Aplite," occurs as a large intrusive 
rani ng m 
variable texture throughout its ‘extent. The greater part is 
of very fine grain, but in part this grades into a coarser 
variety, in which are developed phenocrysts of blue quartz, 
and the ferromagnesian mineral biotite also makes its 
rance. 
The aplite has been fissured, and along these fissures 
quartz veins have been intruded. ssociated with these 
veins occurs a zone of altered aplite consisting essentially of 
quartz and a light-greenish mica. This is a greis 
en. 
further pneumatolytic Rd is the production along fissures 
of white kaolin 
At the south end of the mass there are developed, i in the 
very fine- -grained variety, numerous patches, in cross section 
roughly hexagonal to ellipt tical. On examination these 
patches, or nodules, are seen to consist mainly of quartz and 
tourmaline 
are quartz, 
much chloritized, and muscovi Kaolin .and secondary 
te. 
mica accompany the felspars as alteration products. "4 the 
grained varieties of aplite, biotite and mu are 
of 
E m e coarser varieties. 
sp ai in the coarser vari iioi. In de oi he ' finer- 
Stained e fabric eee the type ''granulitic 
plites 
III. THE QvaRTZ-TOURMALINE NODULES. 
These nodules, on account of their mineralogical com- 
e , Position, resist the attack of the sonnel agents of weathering] 
