642 MR. G. ATTWOOD ON AUEIFEROUS TRACTS OF 



" almandite." The excess of silica in the form of crystalline 

 quartz found by the microscope was confirmed by the chemical 

 analysis. 



At the east end of the Melkote Section a very hard, crystalline, 

 gneissic rock is seen, standing, in some places, from 30 to 40 feet above 

 the ground, and above the banks of the Lokapavani E-iver. The rock 

 has a light grey colour, and contains quartz, mica, and felspar (Rock- 

 section no, 5), and has all the appearance of belonging to an 

 ancient series. Small bands of talc- and chloritic schist * are 

 abundant at the east end of the section, as well as small quantities 

 of haematite and magnetite. A few pieces of coarse corundum were 

 picked up on the surface. 



In traversing the Melkote Area and also most of the schistose 

 bands on the Mysore plateau a deposit is met with which is some- 

 times found in the nullahs (water-courses) on the side hills on 

 masses of broken quartz (the detritus of ancient alluvial gold 

 washing), and also in excavating below the surface where the ground 

 is more or less soft and covered with alluvium or contains fissures 

 and crevices. The native name for the deposit is " Kunker." The 

 de])osit was found to be a calcareous one, generally of a dull and 

 greyish- white colour and of a nodular and botryoidal form. 



A piece of the deposit was selected for analysis and afforded the 

 author the following results : — 



Per cent. Combinations. 



Silica 7-00 



Carbonic acid 40*70 



Lime 48-53 CaO, CO, .... 86-66 



Magnesia 1-27 MgO, CO, .... 2-66 



Alumina 0-13 



Iron protoxide 1-38 FeO, CO, .... 2-22 



Potash 0-13 KO, CO, .... 0-19 



Soda 0-176 NaO, CO," .... 0-30 



Chlorine trace. 



Sulphur ... trace. 



Water 41 



99-726 

 Specific gravity, 2-81. 



It is not unreasonable to suppose that the lime contained in the 

 deposit is derived in a great measure from the hornblende- schists, 

 as the latter contain from 7 to 20 per cent, of lime, whilst the mica- 

 schists are almost devoid of it, and even the gneiss seldom contains 

 more than 2 per cent, of lime. 



Lime contained in rocks which are exposed to a tropical sun 

 weathers awa}^ rapidly. An analysis of a hard diabase rock from 

 South America showed the unaltered rock to contain 9-65 per cent, 

 of lime ; a portion of the same stone weathered contained 4-98 per 



* The natives call all stones of the magnesian order which have a greasy or 

 soapy feel " Balapam," and they use the stone extensively in the construction 

 of their iron- and steel-furnaces, and also in their dwellings. 



