378 MANGANESE DEPOSITS OF INDIA : GEOLOGY. [ PaRT II : 
and H. S, Pattinson of Newcastle-on-Tyne, on behalf of Messrs. C. H. 
B. Forbes & Co. of Bombay, with the following results^ 
A.690 
A. 691 
A.01J3 
Si02 
2-63 
5-20 
110 
A1203 
46-32 
54-10 
57-48 
re203 
19-36 
6-18 
4-61 
Ti02 
5-60 
6-50 
6-55 
Cr203 
0-63 
trace 
013 
CaO 
nil 
nil 
nil 
MgO 
0-29 i 
0-07 , 
0-24 
007 
SO2 
n il 
nil 
P2O5 
0-22^ 
015 
008 
H2O (combined) ...... 
24-51 
27-60 
29-66 
0-40 ' 
-771 
r_: 
0-10 
0-40 
10003 
100 07 
J 
100 08 ' 
From the foregoing analyses it is at once evident that there is a sort 
of progressional change in composition from that of the original basalt 
(or andesite), through the decomposed lavender-grey rock to that of baux- 
ite. This change takes the form of an increase in the amovmts of alumina, 
titania, and water, with a decrease, amoimting to almost total disap- 
pearance, in the quantity of silica, lime, magnesia, and alkalies. Had 
an analysis been given of one of the ferruginous varieties of laterite, 
it would have been seen that there is an increase in the quantity of iron 
oxide also. In this case, as with the bauxites, it probably would have 
been found that manganese was absent. It can be considered almost 
certain that the soft lavender-grey rock, judging from its structure and 
composition, is an altered amygdaloidal earthy trap, but it does not neces- 
sarily follow from the analyses given above that this altered rock passes 
gradually into laterite. In the pit mentioned above, however, there 
1 PuUished bv the kind ocnnission of this firm. 
