Yol. 69.] PETE0L0G-V. OE THE KALGOORLIE GOLDEIELD. 625 



The first description of the microscopical characters of rocks from 

 Kalgoorlie was made hy Mr. G. W. Card, 1 who examined specimens 

 collected by Prof. Frecheville and Mr. Pittman. The amphibolites, 

 in his opinion, had little or no connexion with the auriferons 

 country-rock or with the ore-deposits, and consequently received 

 little notice. The mineralogical composition and structure of the 

 other rocks left him in no doubt of their igneous origin and close 

 relationship. Eeasoning mainly from two rocks — the one a felspar- 

 porphyry, the other an apparently acid rock containing large 

 crystals of quartz and felspar — he concluded that he was dealing 

 with an acid complex of varying texture and structure, granitic in 

 places and felsitic in others. Since the abundant chlorite of the 

 supposed granitic rocks (in reality, derivatives of quartz-dolerite) 

 could not be ascribed to the alteration of some earlier ferromagnesian 

 mineral, he described it as a ' pigment,' and supposed that it had 

 been introduced into the rocks by solutions. Mr. Card's description 

 of the mode of occurrence of the quartz in the quartz-dolerite 

 derivatives as ' islands ' in an ' archipelago ' was very happy, and 

 has been freely adopted in this paper. 



About the same time, Prof. W. W. Watts 2 contributed a note on 

 a rock from a locality south of the Great Boulder Main Reef CM., 

 describing it as a 



' quartz-diorite with (?) two felspars, green altered hornblende, quartz, and 

 micropegmatite.' 



This rock was doubtless a quartz-dolerite amphibolite, the uralite 

 being considered by Prof. Watts as original. 



In the same year Mr. G. J. Bancroft 3 recorded the presence of two 

 dykes, the rocks of which were determined by Prof. J. P. Kemp as 



' pyroxenite composed mostly of tremolite or actinolite.' 



The country-rock of the rich area, which had a bluish tinge, was 

 described as an altered basic eruptive, now containing serpentine 

 and olivine. A greenish unproductive rock was said to be similar, 

 except for the occurrence in it of olivine. The bands of graphitic 

 schist were described, again on the authority of Prof. Kemp, as 



' true slate, probably an altered and metamorphosed clay-rock.' (Loc. cit.) 



In a separate paper Prof. Kemp 4 gave more detailed descriptions of 

 the pyroxenites and graphitic schists. 



1 ' Report on some West Australian Rocks ' Ann. Rep. Dep. Mines, N.S.W 

 for the Year 1897, Sydney (1898) p. 192; 'Notes on the Country Rock 

 of the Kalgoorlie Goldfield ' Rec. Geol. Surv. N.S.W. vol. vi (1898) pt. 1 

 pp. 17-42. 



2 In E. Halse, ' Observations on some Gold-bearing Veins of the Coolgardie, 

 Yilgarn, & Murchison Goldfields, Western Australia ' Trans. Inst. Min. Eng 

 vol. xiv (1897-98) pp. 289-311. 



s 'Kalgoorlie (Western Australia) & its Surroundings' Trans. Am. Inst. 

 M. E. vol. sxviii (1898) p. 92. 



4 ' Geological Occurrence & Associates of the Telluride Gold-Ores ' Mineral 

 Industry, vol. vi (1898) pp. 318-19. 



