Chap. XII.] kodurite series : composition. 
261 
The figures showing the original specific gravity of the rocks were 
calculated from the mineral composition of the rocks given above. It is, 
of course, easy to turn these original mineralogical analyses into the 
original chemical analyses of the rocks, the results being as follows : — 
Kotakarra Boirani 
kodurite. kodurite. 
Si02 .... 47 45 .... 53-30 
AI2O3 .... 18 00 .... 10 -31 
Fe203 . . . . 1 91 . . . .4-17 
FeO . . . . 4-10 . . . . 0 79 
MnO .... 9-08 . . . . 0'98 
CaO . . . . 10 37 . . . .12-54 
MgO . . . . 0-13 . . . .0-22 
K2O . . . . G-'J7 . . . .9-75 
Na20 .... (1) 0-33(1) 
Ti02 . . . . 0 29 . . . .0-24 
CuO .... 0-02 .... trace 
P2O5 .... 1-42 .... Ill 
Car2(2) . . . . 0-20 . . . .0-20 
100 -00 100 00 
Assuming these reconstructed analyses to be approximations to the 
truth it becomes at once evident that it is very difficult to regard the 
rocks to which they correspond as anything else than of igneous origin. 
The difference between these rocks and the metamorphic rocks of the 
gondite series is at once seen by comparing these analyses with that 
of a piece of typical gondite shown on page 349. 
1 There is probably a small percentage of soda replacing a part of the potash in the 
Kotakarra rock ; whilst in the Boirani rock also a portion of the 9 '75 of potash is in all 
probability replaced by soda, in addition to the 0-33 of soda, which corresponds to that 
shown in the oiiginal analysis. 
2 The apatite is assumed to be fluor-apatite, although no fluorine is shown in the 
analysis. 
