20fi MANOANESE DEPOSITS OF INDIA: ^tlNERALOOY. [ PaRT I : 
opaque white band;? parallel to the vertical axis c, so that at first sight 
the mineral looks like a felspar with lamellar twiimiiig. The apatite 
with these bands shows a satiny lustre on the fracture surfaces. The 
mineral is also traversed by fairly numerous cleavages parallel to the 
basal plane. 
On page 1073 is mentioned the find at Devada, also in the Vizagapatam 
district, of a large quantity of green apatite in corroded hexagonal prisms 
up to five inches in diameter. Some of the crystals show pyramidal 
terminations. A carefully selected chip of the mineral gives a weak 
reaction of manganese. The apatite is a fluor-apatite and theiefore 
can be designated at length as mangan- fluor-apatite. On a fresh frac- 
ture it shows a beautiful deep sea-green colour. Under the microscope 
in a small chip it exliibits a rich pleochroism, namely w = rich green 
and e = blue-green. Absorption is e > w. The specific gravity as 
determined in the Geological Survey Laboratory on a large number 
of carefully picked small chips is .3"16. 
From the place in which this mineral is said to have been found, it 
is probable that it came from a very coarsely crystallized variety 
of kodurite, in fact from a sort of kodurite- pegmatite. The Kodur 
mineral, which occurs as a veinlet in a spandite-rock, is to be regarded 
as the product of segregation from the mass of manganiferous rock during 
cooling. As therefore this apatite is probably an original mineral, 
and was moreover probably one of the first minerals to crystallize 
out, it is not surprising that it should have taken up a small quantity 
of manganese. 
Probably most of the apatite contained in the rocks of this series 
is more or less manganiferous, though in most cases the apatite is in 
too small grains for this supposition to be tested except at the expense 
of a considerable amount of time and trouble. 
Triplite. 
TripUte is a monoclinic orthophosphate of the formula (RF)RP04 
or R3P2O8.RF2, \vithRr=:Fe andMn, and also Ca and Mg insubordinate 
amount. It is a heavy dark brown to black mineral of specific gravity 
3'4 — 3"8, and hardness 4 to 5" 5 ; and is found at several localities iii dif- 
ferent parts of the world. The amount of MnO present varies in the ana- 
lyses given by Dana from 14'86 to 54" 14%. 
This mineral has been found in India in considerable masses in peg- 
matite near the mica mine, 2 miles S.-E. of the village of Singar in the 
