200 Becker — Auriferous Conglomerate of the Transvaal. 



pressed by Mr. De Launay in his latest work, J 896. Stelzner 

 also inclined to a similar opinion.* 



In discussing Mr. Penning's paper, Mr. W. Topley sug- 

 gested that the water, which percolating through the already 

 formed conglomerates deposited the gold, may have been at a 

 high temperature. In 1890 my friend, Mr. J. S. Curtis, 

 published a paperf on the banket, in which he states that Mr. 

 Gardner F. Williams, now manager of the Kimberley diamond 

 mines, considered the gold in the conglomerate as not alluvial 

 but quartz gold, deposited after the upheaval of the strata. 

 Mr. Curtis accepted this view, considered the deposits as 

 closely resembling lodes, and referred the impregnation of the 

 conglomerates to the action of the dikes. This opinion is 

 based on the angular character of the gold and on the presence 

 of pyrite both in the banket and in the dikes. Had the iron 

 sulphide of the banket been alluvial, Mr. Curtis says, " there 

 would have been pebbles of pyrites." Of course the large 

 proportion of rounded pebbles of pyrite in the banket was then 

 unknown. Mr. Curtis explained the fact that gold is not found 

 in the sandstone by the relative porosity and openness of the 

 conglomerate. The view of the deposits first distinctly ex- 

 pressed by Mr. Curtis is that to which Dr. Koch leans, and 

 which is adopted by Messrs. Hatch and Chalmers, and by 

 almost all the engineerson the Witwatersrand. Messrs. Hamil- 

 ton Smith and John Hays Hammond consider a portion of 

 the gold detrital and a portion as a deposition from solution 

 after the uplift of the rocks. 



None of the theories are free from objections, real or 

 specious. The impregnation theory implies that there must be 

 deep fissures through which the auriferous solutions obtained 

 access to the once-barren banket beds, and that the solutions 

 permeated the coarse beds to the practical exclusion of the 

 finer sandstone strata. A system of fissures such as would be 

 needed to convey metalliferous solutions certainly exists in the 

 dikes and faults so abundant on the Rand. There are also less- 

 pronounced partings or joints, often nearly parallel to the con- 

 glomerate beds. These last are very important in stoping the 

 ore, and they are well known to all managers. All of these 

 dislocations were produced during the upheaval of the beds 

 from a nearly horizontal position into that which they now 



* In 1894 Messrs. Sclimisser, Stelzner, Suess and Zirkel testified before the 

 Silver Commission in Berlin. The first two regarded it as an open question 

 whether the gold of the banket is detrital or a chemical precipitate contempora- 

 neous with the formation of the beds of puddingstone. The others were con- 

 vinced that it is detrital, Zirkel adding that the deposits had undergone subse- 

 quent chemical metamorphism. (Kommission behufs Erorterung . . . des Silber- 

 werths. Berlin, 1894. pp. 594-95, et passim.) 



f Eng. and Min. Jour , vol. 49, 1890, p. 200. 



