Vol. 69.] PETROLOGY OF THE KALGOORLIE GOLDEIELD. 643 



Analyses op Western Australian Epidiorites. 



! 



X. 



XL 



XII. 



XIII. 



XIV. 



XV. 



XVI. 



SiO» 



46-27 



46-44 



4655 



48-09 



49-94 



50-98 



50-98 



TiO» 



0-49 



0-42 



1-12 



0-12 



0-52 



0-70 



0-79 



A1 2 :J 



23-85 



20-22 



15-36 



19-77 



19-45 



11-06 



17-09 



Fe 2 3 



1-36 



1-91 



319 



1-43 



— 



5-72 



0-87 



FeO 



3ol 



399 



8-79 



6-99 



7-21 



10-67 



8-35 



MnO 



0-32 



0-22 



0-.45 



0-29 



063 



065 



1-25 



MgO 



665 



919 



9-80 



7-56 



9-64 



5-88 



4-70 



CaO 



14-89 



15-18 



10-56 



11-30 



11-23 



8-09 



9-70 



Na 2 



1-52 



1-05 



1-50 



2-17 



0-90 



2-75 



4-09 



K 2 



0-13 



o-io 



033 



0-07 



0-07 



2-11 



o-io 



H 2 0+ ... 



1-17 



0-06 



1-31 



2-05 



0-73 



1-73 



1-08 



H 2 0- ... 



0-11 



0.18 



0-29 



0-17 



0-06 



0-28 



005 



P 2 5 



Oil 



0-36 



0-06 



— 



— 



— 



— 



CO* 



025 



0-08 



100-71 



0-24 

 0-20 



99-76 



tr. 

 tr. 



0-12 



o-ii 



0-05 



none 

 0-44 



none 

 019 



FeS s 



Totals... 



9931 



100-24 



100-43 



101-06 



9924 



Sp.gr. ... 



— 



3-03 



304 



2-98 



2-94 



2-94 



2-95 



Analyst. < 



J.H.B. 



J.H.B. 



E. S. 

 Simpson. 



(?) C. C. 

 Williams. 



E. S. 

 Simpson. 



C. G. 



Gibson. 



C. C. 

 Williams. 



X. G.S.M. 6874. Homeward Bound G.M., Cue. Bull. Geol. Surv. W. Austral. 



No. 29 (1907) pt. 2, p. 53. 

 XI. G.S.M. 6870. Polar Star G.M., Cue. Ibid. 

 XII. G.S.M. 4417. Yarri, North Coolgardie Goldfield. Ibid. No. 11 (1903) p. 7. 



XIII. G.S.M. 3847. Water Keserve 7745, Cue. Ibid. No. 14 (1904) p. 15; and 



No. 29 (1907) pt. 2, p. 53. 



XIV. G.S.M. 5999. Sunbeam G.M.L. 157, Norseman. Ibid. No. 21 (1906) p. 119. 

 XV. G.S.M. 3751. Camp E.B. 32, Charnley River, Kimberley. Analysis hitherto 



unpublished. 

 XVI. G.S.M. 5088. Tower Hill G.M.L. 4387, Leonora. Op. cit. No. 13 (1904) p. 19. 



(i) Derivatives of Quartz-Dolerite. 



The rock here named quartz-dolerite was originally a coarse- 

 grained intrusive rock, such as that of Carrock Fell, termed by Mr. 

 Harker a ' quartz-gabbro ' and by Prof. Rosenbusch a ' quarzdiabas.' 

 The original presence of such a rock in Kalgoorlie is demonstrated 

 most clearly by the study of epidiorites with micropegmatite, but 

 might be directly inferred also from some of the greenstones in 

 which the original structural relations are not entirely obliterated. 

 From these clear types one is led on by gradations to rocks of a very 

 nondescript character, the parentage of which would be doubtful if 

 they were found isolated. All the various kinds of derivatives, when 

 taken together, are found to form a broad band traversing the entire 

 field in a north-north-westerly and south-south-easterly direction, 

 and swelling out into a roughly boss-shaped mass in ' The Mile.' 

 The boundaries of this mass are determined by a complex system 

 of faults, but the northern and southern bands have the appearance 

 of a dyke in situ. From the eastern side of the boss other 

 thinner dykes run for some distance north and south. 



It will be convenient, in description, to group the rocks under 

 three main types. 



