DR. J. A. THOMSON OX THE 



[Dec. 1913,. 



Analyses oj Albite-Granites, Albite-Pe&matites, etc., prom 

 Western Australia. 



XXXIX. 



X L . 



XLI. 



XLIL 



XLIII. 



XLIV. 



Si0 2 



72-77 

 0-55 



13-87 

 tr. 

 2-79 

 0-22 

 0-40 

 1-60 

 4-18 

 2-81 

 029 

 0-02 



0-24 



tr. 



99-74 



2-69 



J.H. 



Brooking. 



70-82 | 70-27 

 035 0-12 



15-56 16-11 

 0-51 0-97 

 1-73 122 

 0-13 i 0-20 

 0-87 1-87 

 2-20 1-76 

 5-57 4-64 

 1-94 0-64 

 0-27 1-08 

 0-05 1 0-10 

 tr. 1 0-12 

 0-40 j 0-20 

 0-20 1 0-09 



100-60 99-39 



2-64 j 2-70 



E. S. E. S. 

 Simpson. Simpson. 



68-36 



18-74 

 none 

 1-15 

 0-45 

 0-54 

 0-39 

 10-22 

 0-07 

 0-93 

 none 



100-85 



2-64 



,E.S. 



Simpson. 



68-11 



0-74 

 15-77 

 0-11 

 2-99 

 0-16 

 1-75 

 3-79 

 4-58 

 0-76 

 0-86 



o-ii 



0-28 

 0-21 

 0-17 



66-43 



0-68 

 16-22 



0-54 



1-17 

 none 



1-60 j 



5-88 



6-35 



0-35 



0-26 



020 



0-40 



none 



0-04 



100-12 

 2-70 



c. c. 



Williams. 



Ti0 2 



Ah0 3 



Fe 2 3 



FeO 



MnO 



MgO 



CaO 



NaoO 



K*0 



ELO + 



ILO- 



P.0 5 



C0 2 



FeSo 



Totals ... 



Sp-'gr 



Analyst ... < 



100-39 



2-74 



E.S. 



Simpson. 



XXXIX. G.S.M. 5392. ' Porphyry,' Duffers' Creek, near Marble Bar. Pilbara Gold- 

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

 XL. G.S.M. 4426. 'Felspar-porphyry,' Mount Catherine Range, Yerilla, North 

 Coolgardie Goldfield. Ibid. No. 11 (1903) p. 7. 



XLI. G.S.M. 8139. 'Soda-granite,' well, 25 chains south of No. 2 Tank. 

 Ravensthorpe. Ibid. No. 35 (1909) p. 21. 

 XLII. G.S.M. 5397. ' Pegmatite (tin-matrix),' Moolyella. Pilbara Goldfiehh 

 Ibid. No. 15 (1904) p. 12. 

 XLIII. G.S.M. 8151. 'Soda-granite,' western well on W.B. 7517, Ravensthorpe. 



Ibid. No. 35 (1909) p. 21. 

 XLIV. G.S.M. 6880. ' Oligoclase-pegmatite,' west of Lily G.M.L. 1494, Cue. IbicU 

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



There are no such albite-granites known near Kalgoorlie. although 

 the presence of tantalum minerals near Coolgardie suggests their 

 presence in that neighbourhood. Nothing is as yet known as to> 

 the relative ages of the albite-granites and the more normal ortho- 

 clase- or microcline-granites which are intrusive into, and have 

 strongly altered, the hornblende-schists of goldfields of the Cool- 

 gardie type. In the Ravensthorpe district, from which only 

 albite-granites and quartz-keratophyres among the acid rocks have 

 been described, there are amphibolites showing considerable contact- 

 alteration, presumably by these granites. If these amphibolites- 

 are correlated in age with those of Kalgoorlie, and it be found 

 that the albite-granites are unrelated magmatically to the amphi- 

 bolites, then the presumption is, either that the albite-porphyries 

 of Kalgoorlie are unrelated to the rocks of the quartz-dolerite 

 series, or else that there are rocks of more than one age in "Western 

 Australia belonging to the spilitic suite. A detailed study of a 



