146 SYSTEMATIC DESCRIPTION OF PRECIOUS STONES 



Wajra Karur is another locality from which a more abundant yield of diamonds 

 was obtained in former times than is the case at the present day. To emphasise the fact 

 that diamonds are still to be found here, we may mention the stone of 67f carats discovered 

 in 1881, from which was cut a beautiful brilliant of 24f carats, valued at ^12,000. Some 

 of the largest and most famous of Indian diamonds are said to have been found here. ITie 

 occurrence of diamonds at this place is peculiar : they lie loosely scattered about on the 

 surface of the ground, and there is no definite diamond-bearing bed. The rocks at the 

 surface are granite and gneiss, and the diamantiferous Banaganapalli sandstone has not 

 been detected in the district. The diamonds are often washed out of the soil by heavy 

 rains, and are then picked up casually, or an organised search for them may be made by 

 the people of the district. 



In order to explain the peculiar mode of occurrence of diamond at this locality, it has 

 been supposed that in earlier geological times a diamantiferous bed covered a large area in 

 the neighbourhood of Wajra Karur, and that this has since been entirely removed by 

 denudation, leaving the diamonds behind as an unalterable residue. Although there is 

 nothing impossible about this view, it is supported by no definite facts. 



Later investigators have attempted to explain the mode of occurrence of diamond in 

 this district in other ways. To the west of the town of Wajra Karur a pipe of blue rock, 

 very similar in character to a volcanic tuff, was found in the granite or gneiss. This 

 closely resembles the richly diamantiferous rock of Kimberley, in South Africa, and was 

 therefore supposed to be the original mother-rock of the Wajra Karur diamonds. This 

 bluish-green, tuftaceous rock, with interspersed blocks of gi'anite and gneiss, was worked on 

 a large scale by an English company with absolutely no success, not a single diamond 

 having been found. 



More recently another solution of the problem has been offered by the French traveller, 

 M. Chaper, who searched the district for diamonds in 1882. This explorer found that the 

 siu'face rock lying just beneath the soil, which in the neighbourhood of Wajra Karur is. 

 gneiss, is penetrated by numerous veins of various igneous rocks. These veins very 

 frequently consist of a coarse-grained, rose-red or salmon-coloured pegmatite containing 

 epidote (pegmatite being a special variety of granite). In the upper, much-weathered 

 portion of such pegmatite veins M. Chaper himself collected two small diamonds, which 

 were accompanied by irregularly bounded grains of blue and red corundum (sapphire and 

 ruby) as well as by other minerals. The two diamond crystals were octahedral in form 

 with perfectly sharp edges, and showed no signs of having been water-worn. Numerous, 

 diamonds are said to have been found under the same conditions by the natives. Chaper 

 was convinced that the diamonds he collected had been originally formed in the pegmatite, 

 and had been loosened from it only by the weathering of the matrix. This theory would 

 of course apply equally well to all the other regularly developed crystals of diamond found 

 at the same place. 



The Indian geologist, Mr. R. B. Foote, has raised a doubt as to the correctness of 

 Chaper's observation, and specially of the deduction he drew therefrom, suggesting that the 

 French traveller was deceived by his native attendant. A confirmation of Chaper's statement 

 is much to be desired, since it would be of considerable help in elucidating the general 

 problem connected with the identity of the original mother-rock of Indian diamonds. The 

 original matrix of all Indian diamonds may possibly have been similar in character to 

 the rock in the neighbourhood of Wajra Karur, the weathering and breaking down of' 

 which has given rise to the sandstones and conglomerates in which the diamonds are now 

 found, but which cannot under any circumstances be regarded as their place of origin. In. 



