1871.] SHA-W DIAMOND-FIELDS OF SOTJXn AFRICA. 27 



the paper was by M. Hiibner regarded as melaphyre, and that in. 

 some parts of the Vaal valley the beds of the Karoo formation might 

 be seen in situ. He disputed the possibility of any of the gravels 

 being of glacial origin. He was convinced that there were no me- 

 tamorjDhic rocks on the western side of the Draakensberg ; those 

 regarded as such probably belonged to the Karoo formation. 



Prof. Texnant commented on the large size of the diamonds from 

 the Cape, of which he had within the last few months seen at least 

 10,000, many of them from 30 to 90 carats each. Some broken 

 specimens must, when perfect, have been as large as the Koh-i- 

 Noor. 



Mr. ToBiN corroborated the information given by Mr. Stow, and 

 stated that the source of the Vaal was in sandstone, and that it was 

 not until it had traversed some distance that agates, peridot, and 

 spinel were met with. The large diamonds, in his opinion, occurred 

 principally in old high-level gravels, at a considerable elevation above 

 the river, which had much deepened its vaUey since the time of their 

 deposit. At Du Toit's Pan, however, none of the diamonds, nor, 

 indeed, any of the other stones, showed any signs of wear ; and he 

 considered that at that spot was one of the centres at which dia- 

 monds had been found in their original matrix. 



Mr. Daintree stated that in Australia there were agate-bearing 

 beds of amygdaloid greenstone, similar to those in South Africa, and 

 that he had called attention to their existence in the neighbourhood 

 of the Burnett river, where since then a diamond of the value of 

 .£80 had been discovered. 



Prof, MASKELYifE commented on the dissimilarity of the minerals 

 found in the diamond-bearing beds of Brazil from those of Du Toit's 

 Pan or of South Africa generally. He thought that possibly the 

 mineral described as peridot might be bronzite, which, however, 

 came from igneous rocks ; and the remarkable fact was that with 

 this and garnet occurred unrolled natrolite, and diamonds in an 

 equally unrolled condition — ^which was suggestive of their having 

 been due to a common origin. 



Mr, "Ward gave an account of an examination of some of the rock 

 from Du Toit's Pan, with the view of discovering microscopic dia- 

 monds, none of which, however, had been found. 



Prof, Etjpert Jones had been equally unsuccessful in the search for 

 minute diamonds, both in sand from Du Toit's Pan and in ochreous 

 gravel from Klip drift. He pointed out the waterworn condition of 

 the agates from Du Toit's Pan, which showed aqueous action, though 

 there were also several other minerals present in a perfectly fresh 

 and unrolled condition. He thought a careful examination of the 

 constituent parts of the gravel might ultimately throw Kght on their 

 origin. That fiuviatile action was sufficient to account for their 

 presence had already been shown by Dr. Kubidge and others, who 

 had treated of the grand plateaux and denudations of the district 

 under notice. 



