150 
MANGANESE DEPOSITS OF INDIA: MINERALOGY. [ ParT 1: 
able to add considerably to the original description, and propose to give 
here a general account of the mineral. 
As will be seen by consulting the sketch-plan of the Kajlidongri 
Occurrence deposit given on Plate 19, the chief spot for this 
mineral is at the north end of the deposit, where 
the rocks containing it form a band about i feet thick, with a strike and 
dip conformable to that of the ore-deposit. ^ The associated rocks had 
not been clearly exposed at the time of my visit, but it looked 
as if the winchite-bearing rocks formed one wall of the deposit at 
this point ; they were probably formed by the metamorphism of 
calcareous manganiferous sediments, accompanying the ordinary 
manganiferous sediments Siom which the ore-body proper was formed 
by metamorphism and subsequent chemical alteration. The band 
m which the Avinchite occurs is made up of layers, ranging up to 4 
mches in thickness, of various composition, nearly all of them containing 
winchite. The most characteristic rock is one composed of winchite, 
calcite, quartz, and the magnesian variety of braunite of which an 
analysis is given on page GH. Another common occurrence is in a rock 
that may be described as a very fine-grained white or pale grey quartzite 
containing abundance of lavender-coloured winchite with greenish spots 
and crystals of blanfordite. This rock is usually banded and is often 
friable so as to simulate a sandstone. Besides these two varieties there 
are several others of less importance, which contain some or all of the fore • 
going minerals, with some or all of the following minerals in addition — 
plagioclase, apatite, crimson mica, and talc. In the rock first mentioned, 
which from its structure may be called a winchite-schist, the winchite 
is usually in more or less flattened crystals tending to be of a bladed 
shape. They are of a light blue colour, with perhaps a tinge of lavender. 
Owing to the predominance of this mineral the whole rock is of a striking 
light blue colour. In the quartzites mentioned above the mineral 
occurs either as radiate tufts of lavender colour on the parting planes 
of the rock, or as small isolated prisms, often beautifully formed, 
which may be either of a rich deep cobalt blue with a tinge of lavender, 
or, when smaller, of a rather dark lavender colour. Sometimes, as noticed 
on page 128, the radiate tufts have blanfordite of green colour in the 
centre with peripheral winchite. In the schist the winchite individuals 
usually range from 0 5 to 2'0 cm. in length. In the quartzite they 
range from 1 or 2 mm. up to perhaps as much as 1 cm. This mineral 
also occurs, though but sparingly, in the vitreous quartzites adjacent to 
^ An unimportant occurrence in nnotiier part of tk« deposit is noticed on page 08(). 
