seme other portions of Mysore. 



yellow, then a yellow with a tinge of green, and finally it assumes a sort 

 of snipbnr yellow or siskin green, the scales of mica scarcely percepti- 

 ble. When, however, the mica is in contact with or near a vein of quartz, 

 it becomes of a pinkish hue, most likely from the higher oxydation of 

 the iron in the cjuartz. Immense masses of mica are often seen lying 

 at the bottom of many of these nullahs, and feeling very greasy when 

 touched — indeed mica in many parts of Mysore is very greasy in de- 

 composition, approaching to talc, a talcose mica, or passing into chlorite. 



It is perhaps the decomposition of a species of talc-mica with felspar-, 

 which affords the very fine white soft and greasy earth found in some 

 of the nullahs, called by the natives shidi munnu, and used occasional- 

 ly for white-washing their houses. In looking at the different appear- 

 ances of decomposing mica in the nullahs, one is led to believe what 

 Dr. Thomson says " that it is pretty evident more than one species is at 

 present confounded together under the name of mica, though we have 

 not yet data sufficiently accurate to separate them with accuracy from 

 each other." Magnesia he mentions as one of the constituents of black 

 mica, audit is very probable that magnesia enters into the composition 

 of the micas generally through Mysore, forpotstone, a magnesian minerals 

 is very common through the whole country, although not so in the im- 

 mediate neighbourhood of Bangalore. The mica and felspar are both 

 very abundant in the gneiss rocks—the mica, as mentioned above, gene- 

 rally of a black colour, and is dispersed through the rock, or in nests or 

 even beds, and sometimes in very small thread like streaks. I have ob- 

 served when there are large beds a good deal of golden mica is mixed 

 up with it. The felspar is generally white, but frequently of a reddish 

 tinge. The large crystals are often of a light red or pink colour, and 

 when there is nearly a total absence of mica, and the rock approaches to 

 or becomes pegmatite, the reddish felspar predominates. 



What is called red granite by Dr. Buchanan I have found in several 

 places in Mysore. I picked up a few specimens to the west or south- 

 west of a very fine bund near the fort — there were no rocks of it, but 

 merely some pieces lying on the ground — the rocks having undergone de- 

 composition. The second place I have met with it is between Closepett 

 and Chinepatam,and the third place between Mundium and Seringapatam. 

 The specimens vary a good deal, but the quantity of felspar of a red colour 

 is very great, and this felspar is of a clayey aspect and peculiar. The spe- 

 cimens from near the bund are alone of this red clayey looking felspar, with 

 glassy quartz, making it a pegmatite. Those between Closepett and 

 Chinepatam are of looser texture, consisting almost altogether of this 

 clayey looking red felspar, with a few crystals of quartz, and numerous 



