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MANGANESE DEPOSITS OF INDIA : MINERALOGY. [ PaRT I 
R. D. Oldham says^ 'In the Tons below Anu there are exposures, 
of a brown ferruginous and dolomitic limestone, passing into crystalline 
ankerite in places which I have conjecturally correlated notwithstanding 
its lithological difference, with the Chakrata limestone.' The Chakrata 
limestone is one of the pre-cambrian formations of the Himalaya and 
is found in Jaunsar in the Dehra Dim district. The specimen (6'403) 
of this rock is of a general huffish colour with grey specks. Its G. = 
2-75. Other specimens in the Geological Survey collection labelled as 
ankerite were collected by Mr. Oldham on the 'cart road below Sairi' 
(6'440), and in the 'Jumna valley about 3 miles above the bridge on 
the old Mussoorie road' (6-438 and 6-439). Both these places are in 
Jaunsar, the latter being in lat. 30° 33', long. 78° l\ The Jamna valley 
specimen is a fairly coarsely crystallized rock showing a rhombohedral 
carbonate of cream colour with a brownish tinge. The faces of the 
carbonate are often curved and exhibit a pearly lustre like that of dolo- 
mite. The rock contains a large number of small crystals of pyrite, often 
altering to limonite, and also shows brown bands, probably due to iron 
oxide. It has a specific gravity of 2-97 and reacts for manganese, iron, 
calcium and magnesium. 
Rhodochrosite. 
Although a rare mineral in India rhodochrosite is one of the minerals 
that, if found in quantity, constitute a valuable ore of manganese. It 
is a carbonate of manganese corresponding to the formula MnCO^ with 
a theoretical percentage of manganese =47-83. The mineral is white, 
pink, or light brown, in colour, with a rather pearly lustre. Its streak 
Cliaracters. white. It is easily scratched by a knife 
(H = 3-5 to 4-5), whilst it effervesces briskly 
with warm dilute hydrochloric acid, and is distinguished by this pro- 
perty, as well as by its inferior hardness, from rhodonite, which it other- 
wise resembles somewhat closely in external aspect. According to Dana 
G. = 3-45 to 3-60 and higher. This ore has been extensively mined in the 
French Pyrenees and at a few other localities. Before it is charged into 
the smelting furnaces, however, it has to be roasted to remove the carbon 
dioxide, leaving an oxidized product intermediate in composition between 
MnO and Mn.^O^, which would correspond, if the original ore were pure, to 
1 Bee. O. S. I.. XVI. p. 194,(1883). 
