156 
THE OCCURRENCE AND ORIGIN OF CERTAIN QUARTZ- 
TOURMALINE NODULES IN THE GRANITE OF CAPE 
WILLOUGHBY. 
By C. E. Tizrey, B.Sc., A.I.C., Demonstrator in Geology and 
Mineralogy, University of Sydney. 
(Communieated by Professor Walter Howchin.) 
[Read July 11, 1919.] 
Piates XXIII. anp XXIV. 
CONTENTS. Page. 
I. INTRODUCTION : ee n iis see ta 6’ 
II. GENERAL DESCRIPTION s E GS 
III. Tue Qvante-Toumsstase heme = uot ANN 
IV. Sum i ; Ln c BE 
I. INTRODUCTION. 
The present paper is devoted to a short description of "s 
essenti- 
developed in a mass of aplite intrusive into the granitic 
headland of Cape Willoughby, Kangaroo Island. The paper 
really forms part of a more extensive study of the petrology 
of the Cape Willo oughby granite "n its allied intrusions. 
The publication of these data is reserved for a later date. 
3 bios Willoughby consists of a large ss of granite 
EN a series of quartzites, quartz-mica-schists, à" 
mica-schists of probably Cambrian Age. The granite 1s an 
*€ven-grained rock consisting of quartz, microcline, plagioclase 
= (oligoclase-andesine), and biotite. Under the microscope the 
on. pice! seen to be muscovite, apatite, and gen 
ihe most feature of the rock is the rae 
idiomorphic satis of quartz showing a baba Oe is 
: orphan ioe This granite occupies an area of approximately 
vo o ja eir re miles, and has a coastline length of about five 
_ Into this pe mass are intruded a sa JOE meee 
: and pegmatitic rocks which a : 
