and Diamonds of Sumhhulpore. 1 37 



" Although employed exclusively in this occupation from 

 time immemorial, the Iharas have not the remotest idea of 

 what constitutes the matrix of the diamond. Mr Mawe, in 

 his Account of the Diamonds of Brazil^ states, that ' the only 

 places where diamonds have certainly been found in modern 

 times are the central and southern parts of India proper, the 

 peninsula of Malacca, the Island of Borneo, and the moun- 

 tainous district called Serro Dofrio, and other places in Bra- 

 zil. Neither the rock in which it occurs, nor the other mine- 

 rals with which it is accompanied in Malacca and in Borneo, 

 are at all known. In India it is found in detached crystals, 

 in a kind of indurated ochrey gravel ; but whether or not this 

 is its native repository is uncertain.' 



" The diamonds of Brazil, like those of India, are found in 

 a loose gravel-like substance, immediately incumbent on the 

 solid rock, and covered by vegetable mould and recent allu- 

 vial matter. This gravel consists principally of rounded 

 quartz, pebbles of various sizes mixed with sand and oxide 

 of iron, and inclosing rounded topazes, blue, yellow, and 

 white, and grains of gold. In some parts of the diamond ter- 

 ritory of Serro do Frio, which I visited, the gravel is cement- 

 ed by means of the oxide of iron into a considerably hard con- 

 glomerate, forming rocks and low hills. On the sides of these 

 are water courses produced by the torrents during the rainy 

 season, the beds of which are very unequal and excavated. 

 In these hollows diamonds are not unfrequently discovered. 

 The usual and regular method of searching for diamonds is to 

 collect the disintegrated conglomerate in which they are found 

 at the bottoms of rivers and of ravines, and by a laborious 

 process of washing as long as the water comes off discoloured, 

 to separate the mud from the distinct grains. The residue 

 thus cleaned is subjected to an accurate examination for the 

 diamonds which it may contain. These are distinguished part- 

 ly by their crystalline form, but principally by their peculiar 

 lustre, slightly verging on semi-metallic, but which cannot be 

 adequately described by words. 



" If the above-mentioned conglomerate is not the real ma- 

 trix of the diamond, its true geological situation is unknown, 

 for it has never as yet been discovered in any other rock." 



