1136 
MANGANESE DEPOSITS OF TNDIA : DESCRIPTIVE. \ PaKT TV 
the replacement has taken place in a direction at right angles to the 
strike of the rocks and independently of their nature. Since, however, 
the remnant-s of Dharwar rocks exposed in the manganese -ore deposit 
seem also to have this westerly strike of the ore deposit, the more prob- 
able explanation of the strike of the deposit being roughly at right a ngles 
to the prevailing strike of the rocks in the neighbourhood is that there is 
a local twist in the strike of the rocks, and that it is this that is represent- 
ed in the strike of the deposit. From the evidence of the remnants of 
rocks seen in various places in the workings 1 should say that the rocks 
that have been replaced here are vitreous quartzites, sericitic phyllites, 
subordinate talcoid phyllites, and possibly some vein quartz. 
At first sight the deposit seems to be composed almost entirely of 
huge boulders of ore from 1 to o or jnore feet in diameter, with a com- 
paratively small quantity of interstitial clay. In some places, however, 
there seem to be distinct signs of bedding in the deposit. From the 
transition shown by many of these boulders from wad into psilomelane 
as noticed on page 1130, I am inclined to think that they are not xletrital 
boulders, as might at first sight be thought ; but that they have grown 
in situ by the gradual replacement of quartzites and phyllites, with the 
formation first of wad and later of psilomelane, the residual quartz, 
quartzitCj and lithomargic shale (representing original phyllite), being 
evidence of this change. 
As exposed in the workings, the length of the deposit in a west by 
a little south direction is 352 paces, or say about 1,000 feet. The deposit 
being on the slope of the hill near its bottom, the workings are not hori- 
zontal, but at an angle of about 20°, this probably being about the ori- 
ginal slope of the surface before work was begun. Measured along this 
slope, the width across the middle of the deposit is about 340 feet, equi- 
valent to about 320 feet on the horizontal. From these figures one can 
easily make a rough estimate of the amount of ore in the deposit, if it 
Q ^-^^ ^ J. assumed that the deposit will continue to 
' ■ ' a depth of 50 feet withoiit serious deterioration. 
[At the time of my visit the workings were nowhere deeper than 25 feet, 
and at this depth the ore had not shown signs of any serious deteriora- 
tion.] Taking as the effective length and width of the deposit 800 feet 
and 180 feet respectively, the pmount of ore down to a depth of 20 feet 
800X180X20X62-5X4 
mav be estimated as roughly T^^r. — ^ = 10/, 000 tons, 
^ •' 2240x3 
