62 



SKETCH OF THE 



hornblende is frequently superadded, and this either replaces the mica, or 

 occurs associated with it in the same mass. Besides the above, talcose and 

 chloritic granites also occur, — and these have occasionally scales of mica 

 disseminated through them. The close grained grey granites are gene- 

 rally composed of mica, quartz and felspar, the last of which is sometimes 

 granular. 



The gneisses are also very generally of a reddish color, and this last 

 class of rocks seems to pass into the waved sienitic gneiss, described in a 

 former paper, which passes again into a hornblende rock, with which fel- 

 spar, of a grey color, is frequently associated. This last passes into pure 

 hornblende rock, and into hornblende schist. In all rocks where horn- 

 blende is abundant, and where felspar is associated with it, the latter is 

 almost universally of a grey or whitish color, and a specimen will be 

 hereafter alluded to which was broken from the junction of a hornblende 

 rock approaching to sienitic granite, and a granitic rock with which 

 minute grains of epidote is associated, in which the felspar acquires 

 a redder tint in proportion as it is removed from the hornblende. This 

 might arise from the coloring matter having had a greater affinity for 

 the hornblende than the felspar, when the original constituents of these 

 minerals were in state to enable such affinity to he exerted. 



We shall now turn our attention to the Quartz Rock of this district, 

 a rock which appears to me to be of first rate importance. In treating of 

 the Geology on the route from Baroda to Udayapur, we have had occasion 

 to describe immense beds of this formation, and it is of very abundant 

 occurrence throughout the whole of Central India This rock varies much 

 in its texture in different situations. The purest variety exists in the 

 form of a m hite semi-transparent rock either stratified or very indistinctly 

 so, and sometimes exhibiting large unstratified beds, very frequently of 



