588 JOURNAL, BOMBAY NATURAL HIST. SOCIETY, Vol. XXVII. 



been greatly modified by intermixture with the fresh water deposits. The mass 

 of the rock is broken up with veins and cavities filled in with calcite, 

 quartz and zeolites. Moreover the fact that this trap was never exposed to 

 atmospheric influences must have tended to some extent to make it different 

 from the upper trap. Though it could not have been in a highly molten con- 

 dition when it burst under the sedimentary beds as judged from its scoriaceous 

 nature, yet it seems to have greatly affected some parts of the aqueous deposits 

 as evidenced by the presence of some peculiar boulders in the mass of the 

 trap. These boulders had the appearance of having been severely burnt ; the 

 outside was covered with black knobs, which scaled off at the slightest touch 

 like carbonaceous shale, while the interior of the boulders consisted of a dark 

 brown matrix, probably of fused silica very hard and tough to the hammer, 

 containing a very large quantity of very fine needles of quartz embedded in 

 all positions in the matrix. Or can it be that these boulders are specimens 

 of rocks deeper down in the bowels of the earth carried up by the force of 

 the trap as it made its way through them, as must have been the case with the 

 boulders of diorite found embedded in the volcanic ash near the KoUwad station 

 in Sewi'i f I throw out the suggestion for what it is worth. 



It is a remarkable fact that the previous writers on the geology of Bombay 

 have taken scant notice of the minerals found in the aqueous deposits. Carter 

 who has taken a good deal of pains in describing the fossil remains in these 

 beds makes only a casual reference to the occurrence of calc-spar and quartz. 

 Speaking of the existence of small deposits of granular coal on leaves and of 

 mineral resin, he finds " invariably calc-spar in company with both these sub- 

 stances." Again when he writes about the layers of cyprides he says : "It 

 also has another pecuharity, which is, that it is almost wholly composed of 

 sUex, in the form of amorphous or crystalline quartz." Dr. Buist makes no 

 reference to any mineral while speaking of the Love Grove beds, but in referring 

 to those under the Malabar Hill he mentions mica and " small crystals of sul- 

 phuret of iron, supposed by the natives, when first found, to contain gold." 

 From these stray references one is led to infer that these writers either thought 

 this subject unworthy of much notice or that they did not come across the rich 

 harvest of minerals now found in these beds. The latter was more probably 

 the case considering the fact that deposits of minerals are confined to small 

 sections of the beds. Drs. Carter and Buist have based their remarks on the 

 beds as they appeared at the Love Grove cut of the sluices, and it is quite 

 likely that no striking minerals were found by them at this place. The min- 

 erals occurring in the beds now exposed are a study in themselves and would 

 well repay the labour spent in inquiring into their composition and crystallo- 

 graphy. It is a fact very much to be deprecated that an important city like 

 Bombay should not possess a single standard collection of minerals, and in 

 its absence I can only describe the minerals found by me as they appear to 

 a lay man. 



I. Iron pyrites. The waters which caused these beds were evidently highly 

 charged with iron sulphide as the mineral is found disseminated in varying 

 quantities throughout the mass of the rock. It is more frequent in the lower 

 than in the upper beds. It occurs as fine dust, as globules, rarely as amor- 

 phous masses resembling Chinese characters and more frequently as well formed 

 cubic crystals of various sizes, the largest found being about ^ inch cube. The 

 pyrites varies in colour from brass yellow through golden yellow to copperish 

 brown. It is also found in a dark greenish blue hue giving out iridiscent 

 colours. This peculiar colour seems to be due to the oxydising influence of 

 the atmosphere, for some crystals, which were golden yellow when first picked 

 up, were subsequently, after a few months, found to have taken on this dark 

 greenish blue colour. The cubic crystals have a scaly surface. Twins are 

 very common. The best specimens are found deposited on the crystals of 



