Ixxvi 
MANGANESE DEPOSITS OF INDIA. 
additional minerals present in the rock. Some of these varieties are 
more acid and some of them more basic than the typical kodurite. 
The following is a classification of them according to their basicity :— 
Quartz-orthoclase-rock. ) 
Apatite-quartz-orthoclase-rock. [ Acid. 
Quartz-kodurite in part. ) 
Quartz-kodurite in part. ^ , 
Orthoclase-rock. j Intermediate. 
Kodurite. ^ 
Pyroxene-kodurite. C Basic. 
Biotite-kodurite. J 
Spandite-rock. 
Apatite-spandite-rock. \ 
Pyroxene-spandite-rock. )• Ultra-basic. 
Manganese-pyroxenites. | 
Graphitic manganese-pyroxenites. J 
At Kodur, the more basic members of the series, such as spandite- 
rock, occur as large patches and streaks surrounded by zones of less 
basic composition, such as kodurite, in a general matrix of quartz- 
felspar-rock or felspar-rock, the most acid members of the series. 
Such an arrangement is just such as one would expect had magmatic 
differentiation of the magma set in prior to its eruption. And such 
is taken as the explanation of the mode of association of these various 
rocks. 
As the result of the analysis of two specimens of opalized kodarite 
from Kotakarra in the Vizagapatam district, and Boirilni in the 
Ganjam district, the mineralogical compositions of the unaltered rocks 
have been calculated as follows :— 
Kotakarra 
Boirani 
kodurite.l 
kodurite. 
Apatite .... 
3-36 
2-62 
Orthoclase .... 
41-29 
57-80 
Albite .... 
2-79 
Garnet .... 
55-04 
36-55 
TiO. 
0-29 
0-24 
CuO 
0-02 
trace 
10000 
10000 
Specific graviiy 
3-23 
2-92 
The aiiatite is lower in this analysis tlian it would have been on a large sample of the rock ; for 
tile apatite is arranged in bands in the rock, and the apatite Ibands were scarce In the specimen 
analysed. 
