186 SYSTEMATIC DESCRIPTION OF PRECIOUS STONES 



garnet, ilmenite, vaalite, &c., are met with. It is among these pebbles that the diamond is 

 to be found ; its distribution is, however, extremely irregular, a miner who hits on a 

 favourable spot may make his fortune in a very short time, while his comrades toil on month 

 after month unrewarded by the smallest success. 



The method of work does not differ essentially from that followed in the diamond- 

 washings of other countries or in the gold-washings of the same country. The sand and clay 

 in which the diamonds and other pebbles are embedded, must first be excavated ; this, 

 when the diamantiferous material is overlain by blocks of basalt, &c., of considerable size, is 

 no light task. This material is placed in a cradle, and the clay and fine particles washed 

 away by rocking the cradle under a stream of running water ; what remains after this process 

 is put through a sieve, and the coarse residue, which contains the diamonds, is spread out on 

 a sorting table and the diamonds picked out by hand. This final operation is easily per- 

 loriiied, for the peculiar lustre of diamonds enables a practised sorter at once to distinguish 

 them from other pebbles. 



TTie yield is not very great, only on an average about 15,000 or 20,000 carats a year ; 

 in 1890, however, 28,122| carats, valued at .£'79,231, were obtained ; a production of 

 30,000 carats (about 13 lbs. avoirdupois), is seldom reached, and never exceeded. 



The quality of the yield in part compensates for its small qiiantity, stones from the 

 river diggings being on the average far superior to those from the dry diggings. The 

 average value of the former is in consequence much higher than that of the latter ; for 

 example, in the eighties a river-stone weighing one carat was worth 56*., while a carat stone 

 from Kimberley only fetched on an average 22,?. 9d. 



A few specially large stones have been secured in the river diggings, such, for example, 

 as the " Star of South Africa," a diamond of the purest water, weighing, in its rough 

 condition, 83| carats ; also the slightly yellow " Stewart," weighing 288f carats, which was 

 found at Waldeck's Plant on the Vaal River. 



The sands and gravels in which the diamonds are found in the river diggings are 

 secondary deposits. It has been suggested that these sands and gravels have been derived 

 from a deposit similar to that in which diamonds are now found in the dry diggings, and 

 situated somewhere in the neighbourhood of the spurce of the Vaal River. The denudation 

 of such a deposit would supply the diamantiferous debris carried down by the river. That 

 the diamonds have been transported some distance is shown by their distinctly water-worn 

 character, and in all probability the original deposit was situated somewhere below 

 Bloemhof in the Transvaal, since no diamonds have been found above this town. The fact 

 that very few of the minerals associated with the diamond in the dry diggings occur in the 

 Vaal River is easily explained when we consider that these minerals are not very hard and 

 would be reduced to powder before they had been transported any great distance by the 

 running water ; whereas the harder minerals, found in the basin of the upper part of the 

 Vaal, and now associated in the river deposit with diamonds, would resist the action of the 

 water for a longer period and would be transported over greater distances. Furthermore it 

 is possible that the characteristic minerals of the dry diggings now known may have been of 

 sparing occurrence in these original deposits, if not indeed absent altogether. The higher 

 quality of the river stones as compared with those from the dry diggings does not militate 

 against the truth of this theory as to their origin, since the quality of stones found in the 

 Jagersfontein dry diggings is well above the average ; it simply leads to the conclusion that 

 the deposit from which the river sands and gravels were derived was also above the average 

 in quality. 



