MYSORE TROVINCE, SOUTHERN INDIA. 647 



to grind their gold quartz (fig. 12). The holes were about 8 inches 

 in diameter and about 4 inches deep. 



Fig. 12. — Section of Rock-mortar in Schistose Gneiss. 

 -8 a — ->/ 



Some exposed surfaces had as many as twelve or thirteen mortars, 

 while in other places only two or three were observed. The rock 

 in which the mortars were formed is a schistose gneiss (or a gneissic 

 mica-schist), tough and hard. It appears likely that the old miners 

 crushed up the partially calcined quartz in the stone mortars * and 

 then carried the powdered sand to the water below and separated 

 the gold by washing in wooden vessels. The following sketches 

 (figs. 13, 14) represent two forms of gold-washing vessels used by the 

 natives at the present day, and they are not unlikely to be somewhat 

 similar to those employed in past ages, as mechanical appliances in 

 Mysore are not subject to daily improvements as they are in the 

 western countries. 



There is no evidence about the after-treatment, but on account 

 of the gold consisting, in many cases, of very fine particles, some 

 means of collecting it beyond washing must have been adopted. 

 Fusion of the concentrated material with lead was probably the 

 method employed in ancient days, and in more recent times 

 amalgamation by means of mercury. 



Several other promising quartz-veins were found at the south-east 

 end of the Seringapatam Section, which may lead to further explora- 

 tion. In the northern part of the section the quartz- veins are 

 composed of hard white quartz showing little or no pyritic matter, 

 and apparently devoid of mineral, whilst at the south-east end a 

 great change in the quartz-veins takes place. Pyrite, chalcopyrite, 

 and arsenical pyrites are found, and the vein-stone contains large 

 quantities of iron-oxides, and is more or less banded or divided by 

 seams, while the quartz is of a finer grain, entirely different from 

 that at the north end of the section. 



At the south-east end of the section (see Plan and Section, fiigs. 10, 

 1 1) the schists are much broken up and disturbed by porphyritic dykes. 

 One of the strongest of the dykes was more than 20 feet wide, and 

 had a strike north 80° east (Eock-section no. 8, p. 652). The rock 

 was of a darkish grey colour, very hard and compact, showing felspar- 



* Quartz would be very friable if, after being exposed for some time to a 

 charcoal fire, it had water thrown over it wliils^t heated. 



