ANORTHOCLASE BASALT FROM MAPLETON, QUEENSLAND. 165 



In comparison with the average basalt analysis, the 

 marked deficiencies in magnesia and lime and equally 

 marked excesses of soda and potash are the outstanding 

 features of the anorthoclase basalt. 



An examination of the norms shows a very close 

 resemblance, especially in the felspathic content of the 

 Mapleton and Spicer's Peak basalts. The modes of the 

 two rocks differ considerably, also there is much difference 

 in their textures and crystallinity. 



The felspathic content of the norm of the JMontvill^ 

 basalt is in sharp contrast with that of the Mapleton basalt. 

 The deficiency in potash and the excess in lime of the 

 former is made very pronounced. 



Chemical Analyses, 



« Vole. Rock?, S.E., Qld., p. 177. 

 R.S. M. 



