136 



MIDDLEMISS: THE GEOLOGY OF IDAtt STATE. 



side for comparison, it is clear that the resulting mixture-rock has 

 the composition of a potash syenite from a chemical point of view. 

 Mineralogically, however, it has too much both of quartz and of 

 plagioclase, whilst it has too little orthoclase for it to be called a 

 syenite. From the point of view of the mineral components, then, 

 it stands marked as a mixture rock, not a syenite, such as would 

 have resulted had the molecules been allowed appropriate play 

 under magma conditions, nor yet a simple mechanical entangle- 

 ment of the one rock within the other, but a hybrid rook in which 

 partial chemical reactions only have taken place giving abnormal 

 results : — 





Kaua 



Kaua 



Kaua 



Kaua 





hybrid, 

 as 



hybrid, 



28 



olivine 

 dolerite, 



granite, 



20 





i 6 8 



4 7 1) 



• 8 



6 1 V 











2-72 average 



S. G. 



2-83 



2-87 



3-00 



of 3 speci- 

 mens. 



SiO, 



63-64 



57-20 



60-23 



0604 



AU) 3 . 



14-28 



14-78 



16-51 



14-77 



Fe.O, . 



2-68 



2-12 



3-83 



1-18 



FoO 



0*24 



7-43 



8-20 



4-41 



MgO 



102 



3-23 



6-48 



0-98 



CaO 



t-38 



6*48 



0-53 



2*96 



Na.,0 



[•98 



2-26 



2-07 



2-56 



K,6 



3-90 



3-00 



1-04 



5-25 



RlO (below 108° C.) 



•09 



•11 



•08 



•21 



B a (above 108° C.) 



•91 



1-39 



•63 



•71 



Til) 2 



1-63 



1-70 



1-41 



•69 



ZnO, 



•01 



•01 



trace 



•03 



CO, 







trace 





P.O, . 



•24 



•32 



•31 



trace 



CI .... 



trace 







(race 



( Total S as) S0 3 



•05 



•06 



•23 



trace 



Cr,0, 





•01 



■01 





MnO 



•11 



•13 



•14 



•11 



BaO 



•07 



•05 



•02 



•02 



SrO 



trace 



trace 



trace 



(race 





100-03 



100-20 



99-78 



99*91 



A few additional points that may be noticed with reference 



Additional remark*. t0 . tllC c]wm] ™ ] aild mineral composition of 

 this hybrid rock arc, first, the specific gravity. 



