Chap. XXXVTT. 1 
GOA : DAB DABBA. 
987 
rock exposed is laterite. Of this rock there seems to be a great 
variety, from the ordinary ferruginous laterite free from manganese-ore 
to rock showing all the structures of laterite, but composed almost 
entirely of pyrolusite. The ferruginous part of the laterite consists of 
some variety of limonite, either yellow ochre, or the brown compact 
limonite, or some intermediate variety. Some of the ferruginous portion 
may be ferruginous clay. Besides the pyrolusite, there is also a little 
psilomelane present in the form of thin veinlets in the ferruginous 
laterite. The excavations must be some 25 feet deep. In the lower 
parts a few patches of residual quartzite are to be seen. These 
quartzites are soft and white and show the same network of pjTolusite 
as at Fanuswiidi ; and, as before, the evidence points to the laterite 
having been formed by the impregnation and replacement by iron 
oxides of the quartzites, in which the manganese -ores had already 
formed. On this interpretation, at least a portion of the manganese-ore 
in the laterite, may, as at Fanuswadi, be taken as representing the 
manganese-ore contained in the quartzite before it was replaced. On 
the other hand a portion of the manganese in the laterite may have 
been introduced at the time of formation of the laterite. That portion 
of the manganese in the laterite that represents the manganese-ore in the 
quartzite need not necessarily have retained the precise form in which 
it was present in the quartzite, but has probably been largely re- 
arranged by segregative actions. The ore won here is practically all 
pyrolusite. 
3. Dab Dabba II. 
(Shimoga Manganese Company, Ltd.) 
This deposit, which lies on the side of a low range of laterite hills, 
is situated just to the west of the road from Piligaon to Bicholim, a 
little further north than the Dab Dabba deposit belonging to the Goa 
Mining Company. In one opening a bedded limonitic rock striking 
S. 20'' E., with a very steep dip to the east side, was exposed. This 
rock contains a large number of tiny sparkling octahedja, which 
turn out to be magnetite, and is seen through a lens to contain 
quartz also, the whole suggesting a magnetite-quartzite, a large propor- 
tion of the magnetite of which has been converted into limonite. In 
