i084 
MANGANESE DEPOSITS OP INDIA : DESCKIPTIVE, [ pART IV : 
clase-rock containing abundance of spandite and 
Origin of the deposit, . , , , 
pale greenish or greenish blue apatite (quartz- 
kodurite). These two rocks probably occurred as lenticular bands in the 
' country' of felspar-or quartz-felspar-rock. The spandite-rock has, by 
alteration in situ, accompanied by addition of manganese brought in solu- 
tion, yielded a large portion of the ore-body, especially where it is most 
massive. The apatite-spandite-quartz -felspar-rock (quartz-kodurite) has 
also yielded a fair proportion of ore, in which the apatite, quartz and 
felspar have been replaced by manganese oxide brought in solution, the 
manganese -garnets remaining unaltered and scattered through the man- 
ganese-ore (often compact psilomelane with scattered mangan-magnetite) 
thus produced. This rock, as well as the spandite-rock, has at other 
times given rise to manganiferous solutions, which have partly effected 
the replacement mentioned above, and have partly impregnated and 
replaced the bands of felspathic rock separating the original bands of 
spandite -bearing rock. Either previously to, or simultaneously with, 
this replacement by manganese, the felspar of the usually extremely 
felspathic ' country ' has undergone extreme kaolinization. 
If we imagine the ore-body to be divided longitudinally into two 
halves we can say that the southern half of the ore-body consists more 
or less of solid ore, and probably corresponds roughly to the main mass 
of the original spandite-rock. The northern half of the deposit, on the 
other hand, was probably once composed partly of spandite-bearing 
rocks — the manganese of which partly collected 
Constitution of the de- • |. jj^nds of manganesc-ore during the subse- 
posit. . ° , r 
quent alteration of the rock — and partly of non- 
manganiferous felspathic rocks, since converted into lithomarges, wad-, 
etc. This half of the deposit now consists mainly of very soft litho- 
margic rocks, composed of white or variegated pink, brown, or yellow, 
lithomarge, spotted and streaked with black. In many places this 
decomposed rock is quite black and then looks Uk? wad. The 
colouration of these lithomarges and wads is due to impregnation 
and often (in the latter case) partial replacement by oxides of iron 
and manganese ; this impregnation has often taken place up to some 
small crack in the rock (on either side of which it is slickensided), 
so that there is a marked difference in the colour of the rock on the 
two sides of the crack. This is well shown in Plate 51. At the same 
