Vol. 69.] PETROLOGY OP THE KALGOORLIE GOLDEIELD. 621 



27. On the Petrology of the Kalgoorlie Gold field (Western 

 Australia). By James Allan Thomson, M.A., D.Sc, F.G.S., 

 Palaeontologist to the Geological Survey of New Zealand. 

 (Read May 7th, 1913.) 



Contents. 



Page 



I. Introduction 621 



II. Historical Eeview 624 



III. Descriptive Petrography 629 



(«) The Sediments. 



{b) The Fine-G-rained Amphibolites. 



(c) The Fine-G-rained Greenstones. 



(d) The ' Calc-Schists.' 



(e) The Peridotites and their Derivatives. 



(,/') The Hornblende-Rocks (Pyroxenite-Amphibolites). 

 (g) The Lustre - Mottled Amphibolites (Hornblende- 



Dolerite-Amphibolites). 

 (h) The Epidiorites. 

 (i) Derivatives of Quartz-Dolerite. 

 (j) The Porphyrites. 

 (k) The Albite-Porphyries. 

 (I) The Jaspers and Graphitic Schists. 



IV. Relationship of the Rocks 662 



(«.) Relationship of the Peridotites to the Quartz- 

 Dolerite Series. 



(b) Relationship of the Porphyries and Porphyrites to 



the Quartz-Dolerite Series. 



(c) Connexion of Gold and Tellurides with Igneous 



Magmas. 

 (cl) Relationship of the Quartz-Dolerite Series to the 

 Older Amphibolites and Greenstones. 



V. Summary and Conclusions 671 



VI. Postscript 672 



VII. Bibliography 674 



Abbreviations used. 



E. East Coolgardie Goldfield. The number refers to the register of 

 gold-mining leases. 

 G.M. Gold mine. 

 G.M.L. Gold-mining lease. 



G.S.M. Geological Survey Museum. The number refers to the register of 

 rocks in the possession of the Geological Survey of Western 

 Australia. 



I. Introduction. 



The goldfields of Western Australia may be conveniently considered 

 as forming a series lying between two extreme types. At the one 

 end are fields such as Southern Cross and Coolgardie, lying within 

 the contact-aureoles of granitic intrusions : their rocks are intensely 



