Chap. IX. ] associated non-manganiperous minerals. 
219 
The other place at which arsenates occur is Kajlidongri in the Jhabua 
State, where two different minerals of this group 
The Kajlidongri a. sen- ^^^^ these is in a vein of quartz and 
barytes, traversing the manganese-ore body at 
cross-cut 6 (see Plate 19). The arsenate occurs in sparsely distributed 
rounded crystals up to half an inch long. It is of a sage-green colour 
and looks exactly hl^e apatite at first sight. That it is not apatite is 
indicated by its inferior hardness, between 3 and 4, instead of 5. 
Qualitative examination of the mineral showed it to be an arsenate of 
calcium and magnesium, with small quantities of other constituents. 
The other occurrence of arsenates at this locaUty is in the N, W. spur 
workings at the point shown on the plan of this deposit on Plate 19. Here 
the mineral was found in a rock of which it formed the chief constituent, 
the other minerals present being quartz, spessartite, and braunite. The 
relations of this rock to the manganese-ores with which it was associated 
were obscure and I coald not determine if it were a vein rock or a proper 
member of the gondite series. As seen in a hand-specimen of the rock, the 
arsenate, on account of its cleavage, suggests a green felspar at first sight, 
the coarseness of the rock being about that of an ordinary granite. The 
hardness of the mineral is about 3. Its colour is a pale green. It 
dissolves easily in dilute hydi'ochloric acid on heating and gives reac- 
tions for water and arsenic in the dry way. It was examined qualita- 
tively by Pandit T. S. Kochak in the Geological Survey Laboratory, 
and was found to be an arsenate of magnesium with a very little hme 
and a certain amount of water. Under the microscope the mineral 
is colourless, shows a high refractive index, and polarizes in colouis of 
che second to fourth orders in sections showing first order colours for 
quartz. The cleavages are well marked forming two sets crossing like 
those of calcite. The angle between these cleavages varied from 51° to 
65° in those measured. Lamellar twinning is sometimes shonm as well 
as simple twinning. In some cases the section was at right angles to one 
optic axis, thus showing that the mineral is optically biaxial. 
One of these brushes indicated, in a section in which the angle between 
the two set of cleavage was 60°, that the optic axial plane lies from an 
acute angle to acute angle of the cleavage rhombs. The mineral is often 
?een to be undergoing replacement by oxides of manganese. The 
replacement begins along the cleavage cracks and gradually spreads 
over the whole crystal. The mineral often contains inclusions of yellow 
spessartite, which also undergo alteration to manganese-ore. Thus 
the garnet is idiomorphic with regard to the arsenate ; the latter in its 
