648 
MANGANESE DEPOSITS OF INDIA : DESCRIPTIVE. [PauT IV : 
There is a great variety of manganiferous rocks 
Rocks found amongst these gneisses, but the following are the 
chief types : — 
1. ri/roxene-spcssartite-quartz-rock (pyroxene-gondhe), often with calcite. The 
pyroxene may be rhodonite, a yellow or a colourless pyroxene. 
2. Spessartite-quartz-rock (gondite), with apatite. 
3. Apatite-pyroTene-spessartite-qvarfz-rock. 
4. Apatite-spessartife-piedmontUe-rock with some felsjotir. 
5. Calcite-spcssortiie-quarfz-rock. 
6. Mica-pyroxene-microcline-quartz-manganese ore-rock. The mica is a man- 
ganiferous one with the following pleocliroism : — 
a = pink ; 
13 = pale green ; 
t = orange. 
The pyroxene has the following pleochroism : — 
n = pink ; 
b = lilac; 
£ = blue; 
this is the blanfordite type. 
7. Crystalline limestone with spessartite, quartz, microciine, and apatite. 
8. Crystalline limestone with spessartite, piedmontite, and rhodonite (?). 
9. Wollastoniie-apatite-calcite-qtiartz-spessartite-rock. 
At one spot a vein-like cavity was found traversing one of the pied- 
montite-bearing rocks. In this were found some small but well-formed 
crystals of piedmontite with measurable faces (see page 190). 
Several of the above rocks are of great interest. This remark applies 
especially to No. 4, on accovuit both of the large amount of apatite it 
contains and because of its beauty when viewed in thin slices imder the 
microscope. In several of these manganiferous rocks apatite is so plen- 
tiful as to constitute almost J or J of the rock. 
These manganiferous rocks are, of course, often blackened, owing 
to the partial conversion to manganese-ore, usually braunite. 
The principal non -manganiferous rocks are the following :— 
]. Epidote-kornblende-quartz-rock, with sphene, apatite, tourmaline, wollasto- 
nite, and chalcopyrite. 
■J. Scapolite-garnet-pyroxene quartz-rcck, with calcite and apitito. 
'.}. Q uartz-felspar-woUastonitt-pyiozent-rock. 
4. Quarlz-garnet-pyroxene-rock. 
5. Microcline-biotite-quartz-rock. 
