THE LODES. I 5 



The production of these enlarged ore-bodies by folding is well 

 illustrated on a small scale by a hand-specimen of country rock 

 taken from the neighbourhood of the lode in the Ooregum Mines. 

 The rock consists of hornblende schist seamed with calcite and is 

 folded in exactly the manner described above. With the difference 

 that the veinules are of calcite instead of quartz, all the peculiarities 

 of the folded quartz veins are reproduced in the hand-specimen. (See 

 PI. 1 ; Frontispiece.) 



The diagrams, figs. 2 and 3, drawn from this specimen will serve to 

 illustrate the formation of " chambers " of ore by folding. The thick' 

 ened part of the fold or "chamber" is marked in the figures by a x . 



As to the origin of the folds, there is no doubt that they are the 

 result of enormous lateral pressure acting on the schist beds subse- 

 quent to the formation of the quartz veins, for the quartz in the folded 

 portions of the veins has a peculiar banded hornstone-like structure, 

 which is a result of the great stress to which it has been subjected. 1 



Another noteworthy feature of the Kolar veins is the occurrence 

 of the pay-ore in more or less well-defined " chutes." The distribu- 

 tion of gold in quartz veins in definite areas within the plane of the 

 vein is a well-known characteristic of quartz lodes : but nowhere could 

 a better illustration of the phenomenon be found than on the Kolar 

 gold-field. In the accompanying longitudinal sections the shaded 

 portions indicate the chute-areas as far as proved by present 

 developments. It will be seen that they have a fairly constant dip to 

 the north within the plane of the vein, which itself dips west. This 



1 Mr. Holland describes specimens of this quartz as follows :— 

 " Dark grey quartz with white bands and hornblendic bands and lenses near the 

 margin. Specimens show a tendency to break into regular flat cakes through the 

 prevalence of joint planes crossing one another nearly at right angles. Frac- 

 ture away from joint planes, conchoidal with pitchstone lustre. Films of calcite 

 along the best developed joints. Under the microscope the quartz is seen to be 

 granulated to an excessively fine degree and trained out into bands almost as 

 perfect as flow structure ; nevertheless, the parallelism of many grains gives an 

 approximately simultaneous extinction over a large area. Thin long sheets occur 

 with undulose extinctions, but crystallographically continuous across the 2" field. 

 There are streaks and eyes of foreign minerals, hornblende, felspar, mica and 

 rods of tourmaline." 



