Chap. IV. ] 
RHODOCHROSITE. 
123 
a percentage of metallic manganese lying between 77 and 72. Hence it 
will be seen that although the original ore, even if pure, is considerably 
lower in its manganese contents than the oxidized ores that make up the 
whole of the ore exported from India, yet it may contain after roasting 
a considerably higher manganese percentage than the oxide ores. If 
any large supplies of rhodochrosite or carbonate ores should ever be 
discovered in India, it would of course be advantageous to roast them 
before exporting, on account of the great saving in freight charges that 
would accrue. 
As already mentioned, this miaeral is a rare one in India ; it has up 
to date been found only in the Chhindwjira and Nagpur districts, both of 
them in the Central Provinces. In the Chhindwara district rhodochrosite 
has been fomid at two localities, namely Gaimukh and Devi. At Gai- 
mukh the rhodochrosite occurs in a rock composed of rhodonite and 
rhodochrosite with manganese-ore, the latter 
bemg probably braunite. The rhodochrosite 
is pale pink or pinkish white in colom', and occurs as small interstitial 
patches of pearly lustre between the rhodonite and braimite individuals, 
which form by far the larger portion of the rock. It also occurs in a rock 
composed of spessartite and rhodonite, but only in small quantity. At 
Devi it occurs sparingly as a rock composed of this mineral, 'A-ith a larger 
proportion of rhodonite. Under the microscope it appears that rhodochro- 
site is not so quickly blackened to manganese oxides as rhodonite ; but it 
does also suffer this oxy-alteration. The rhodochrosite is not as a rule 
clear as seen under the microscope ; but is clouded, so that the cleavage is 
usually obscured. In one case where the cleavages were visible they were 
seen to be curved. In one case, also, signs of twinning were detected in 
spite of the clouding of the mineral ; but as a rule rhodochrosite does not 
seem to exhibit this phenomenon. The other microscopic characters that 
the mineral exhibits are absorption and a high birefringence, which do not 
of course enable one to distinguish it from the other rhombohedral carbon- 
ates. Like dolomite it does not stain when treated with Lemberg's stain, 
at least as far as I have been able to ascertain on the clouded specimens 
I have been able to test. At Devi the amount of this mineral in the ore is 
inconsiderable, but at Gaimukh,when the ore-deposit is worked, it may be 
found that almost every piece of ore contains at least a small quantity of 
rhodochrosite. That this will not, however, be large in the aggregate, is 
shown by the analysis of a sample from this locality given on page 784, in 
which the amount of carbon dioxide is only 0 41%, corresponding to 
1-07 of rhodochrosite. In several other of the analyses of manganese- 
