80 
MANGANESE DEPOSITS OF INDIA: MINERALOGY. [ParT I: 
deposited after the formation of the limestones, which contain piedmon- 
tite,* either so as to fill in cavities dissolved out by percolating waters, 
or by the metasomatic replacement of the Umestone under the influence of 
percolating manganiferous solutions. This deposit has been to a certain 
extent quarried with the extraction of a considerable quantity of very 
pure mineral. An analysis of a sample of the mineral is given on page 957, 
and an analysis of a picked piece of the ore in the table on page 82. The 
latter analysis shows the ore to be very pure pyrolusite, the 
most noticeable feature being the extremely small quantity of iron, 
namely 0'04 per cent. Such an ore is admirably suited for glass manu- 
facture, for which it would probably fetch a high price. The ore itself is 
found as beautiful concentric mammillary specimens reflecting a silky 
black lustre from the rounded surfaces of the mammillations, which are 
often of considerable size, namely one inch or more across. Plate 3 
shows a piece of this ore. 
Amongst the ores formed by replacement at the outcrops of rocks of 
the Dharwar series, pyrolusite is very commonly found, as for example, 
at Tawargatti and Chik-Vadvati in the Dharwar district (pages 642 , 645) ; 
in the manganiferous area south of Chaibasa in the Singhbhum district 
(page 619) ; at numerous locahties in the Jabalpur district, especially in 
the rocks known as the Gosalpur quartzites (pages 811 — 814) ; and in 
most of the deposits of Mysore and some of those of Sandur. 
Pyrolusite, for analyses of which see pages 657, 659, is also found at 
Sivarajpur in the Panch Mahals district, Bombay. These ores seem to 
have been formed by the replacement at the surface of the quartzites of 
the Champaner series, the equivalent of the Dharwars of other parts of 
India. 
In the ores of lateritic origin pyrolusite is also one of the commonest 
minerals and is to be found at all the localities where ores of this origin 
are found. For a list of these areas see page 385. There is nothing of 
especial interest to notice about these ores except that they frequently 
show open spaces or cavities hned with small stumpy prismatic or 
flattened crystals which sometimes seem to be proper pyrolusite and at 
others seem to be intermediate between manganite and pyrolusite. From 
their crystalUne shape they may once have been manganite. [A good 
example of pjTolusite formed by the alteration of manganite is figured 
on Plate 22, Vol. XXXIII, Records of Geological Survey of India, the 
specimen figured coming from Ramandrug in the Sandur Hills ; hu 
this is not from true laterite]. Of the lateritic pyrolusites perhaps the 
