Vol. 69.] 



PETROLOGY OF THE EALGOOELIE GOLDFIELD. 



m: 



veins commonly occur, for the vein-solutions alter it to a talcose or 

 carbonate-rock, and the talc-schists are frequently confused with the 

 greenstones. Two serpentines from the West Pilbara Goldfield, 

 which I described in 1909, x differ from those of the Kalgoorlie type 

 in the absence of bastite and tremolite and in the presence of 

 flakes of biotite or chlorite derived from it ; and another Pilbara 

 example (G.S.M. 5375, hills near Box Soak), previously noticed 

 by Mr. E. S. Simpson, 2 is essentially similar. The serpentines 

 described by the last-named writer and Mr. L. Giauert 3 from 

 Ravensthorpe (G.S.M. 8154, 8326) appear to be dunite-serpentines 

 showing incipient alteration to talc and carbonates. Talc-carbonate 

 schists seem to be well developed at Warrawoona, while contact- 

 altered tremolite-talc schists are found in fields of the Coolgardie 

 type. 



Analyses or Derivatives of Peridotite. 





IV. 



V. 



VI. 



VII. 



VIII. 



SiOo 



39-35 



0-60 



6-56 



9-45 



1-57 



28-51 



3-10 



0-73 

 0-15 

 9-05 

 0-14 



none 

 none 



99-21 



2-81 



C.C. 

 Williams. 



31-07 

 0-26 



5-49 



1-49 

 7-64 

 0-18 

 17-49 

 546 



3-82 



o-ii 



0-05 

 0-07 



27-24 

 0-06 



100-43 



2-89 



C. G. 



Gibson. 



33-80 

 033 

 0-02 

 5-72 

 0-50 

 ( trace 7 



I (o-ooo) 5 



0-40 

 8-70 

 0-19 

 1995 

 1-34 

 none 

 0-30 

 2-11 

 0-59 

 0-09 



o-ii 



25-98 

 024 



100-37 



2-97 

 E. S. 



Simpson. 



38-91 



0-06 



1-08 



1030 



1-80 



0-08 



3665 



tr. 



0-40 



1089 



0-28 



none 

 none 



100-45 



E. S. 

 Simpson. 



30-63 

 0-52 



1-68 



5-94 

 4-72 

 Oil 

 32-30 

 tr. 



0-41 



o-ii 



0-52 

 0-15 



23-03 

 0-20 



100-32 



2-91 



E. S. 



Simpson. 



TiO- 



Zi-O- 



AlaOs 



Cr 2 3 



U0O3 



Fe«0 3 . 



FeO 



MnO 



MgO 



CaO 



BaO 



Na«0 ......... 



KoO 



HoO+ 



H>0- 



P 2 5 



COo 



FeSo 



Totals 



Analyst < 



IV. Tremolite-serpentine. G.S.M. 3218. Near Hannan's Lake, Kalgoorlie. 

 Bull. Geol. Surv. W. Austral. No. 6 (1902) p. 75. 

 V. Carbonated serpentine. G.S.M. 375. Island, western side of Hannan's 

 Lake, Kalgoorlie. Ibid. 

 VI. Fuchsite-magnesite rock. Dump a quarter of a mile east of Hannan's 



North, G.S.M. 2139 E, Kalgoorlie. (Analysis hitherto unpublished.) 

 VII. Chlorite-serpentine. G.S.M. 5375. Hills near Box Soak, Pilbara Goldfield. 

 Bull. Geol. Surv. W. Austral. No. 15 (1904) p. 12. 

 VIII. Talc-carbonate schist. G.S.M. 5757. Near Moolyella Gap, Warrawoona, 

 Pilbara Goldfield. Ibid. No. 20 (1905) p. 66. 



1 Bull. Geol. Surv. W. Austral. No. 33, pp. 144 & 147. 



2 Ibid. No. 15 (1904) pp. 12 & 16. 



3 Ibid. No. 35 (1909) p. 39. 



