Yol. 69.] 



PETROLOGY OF THE KALGOORLIE GOLDEIELD. 



659 



Simpson, 1 of which only one (the first) is sufficiently fresh to admit 

 of comparison with similar rocks from elsewhere. The analysis 

 (XXVIII) of the albitized porphyrite is repeated from p. 657 for 

 the purpose of comparison. 





XXIX. 



XXX. 



XXXI. 



XXVIII. 



Si0 2 



TiO 



68-12 

 0-62 



65-51 

 tr. 



18-12 

 tr. 

 2-39 

 0-05 

 0-38 

 2-10 

 4-27 

 3-28 

 0-46 

 0-07 

 2-41 

 0-06 



99-10 



0-46 

 tr. 

 1-73 

 0-05 

 0-38 

 1-99 



62-16 

 0-16 



14-98 

 0-39 

 303 

 0-51 

 1-32 

 4-03 

 6-18 

 1-59 

 0-25 

 0-07 

 5-65 

 0-60 



100-92 



0-58 



3-03 

 0-51 

 1-32 

 4-03 



63-05 

 0-97 ' 

 14-04 



5-36 

 0-02 

 1-58 

 5-92 

 6-74 

 0-62 

 0-26 

 0-04 

 1-47 



100-07 



AloOj 



15-97 

 1-09 

 2-27 



tr. 

 0-92 

 0-71 

 6-03 

 1-29 

 0-29 

 0-17 

 1-13 



tr. 



Fe 2 :! 



FeO 



MnO 



MgO 



CaO 



Na 2 



KoO 



H.,0+ 



H 2 0- 



CO" 



FeSo 



Totals 



Bases soluble in 

 AI0O3 



98-61 



aqua regia : — 



031 

 1-09 

 2-27 

 tr. 

 0-58 

 035 



Feo0 3 



FeO 



MnO 



MgO 



CaO 



Sp. gr 



2-60 



E. S. Simpson. 



2-72 

 C. G. Gibson. 



2-72 

 C. G. Gibson. 



2-75 

 C.C.Williams. 



Analyst 



XXIX. Albite-porpbyry. G.S.M. 1743, main shaft, Boulder Bonanza, G.M.L. 



1064 E. 

 XXX. Albite-porpbyry. G.S.M. 1980, Hannan's Hundred Acres, G.M.L. 1226 E, 



150-foot level. 

 XXXI. Albite-porpbyry. G.S.M. 2219, 700-foot level, Brookman's Boulder, 



G.M.L. 749. 



The felspars may be calculated as before, with the following 

 result : — 



XXIX. XXX. XXXI. XXVIII. 



Orthoclase 7"62 19'38 9"40 3-67 



Albite 52'67 35"39 52"25 56"96 



Anortbite 1'78 0-55 none 6-18 



The amount of potash may probably be taken as a measure of the 

 sericitization, and this may explain why the porphyrite contains 

 more albite than the porphyries. It appears to be the least seri- 

 citized rock of those analysed. Some of the freshest specimens of 

 the albite-porphyries should exceed 60 per cent, of albite, judging 

 from the sections. 



1 Bull. Geol. Surv. W. Austral. No. 6 (1902) p. 73. 



