70 Report S.A.A. Advancement of Science. 



" Muller's " reef lies at the junction of the quartzite and schist, 

 the quartzite being partly replaced by the quartz. Most of the gold 

 in the reef occurs in pockets of haematite which are frequently of 

 cubical form, and perfect pseudomorphs after pyrites. Some of 

 this haematite is very rich in gold. 



Black Reef Series. — The Black Reef series appears at the 

 southern end of the Nondweni goldfield, and near Denny Dalton and 

 Ulundi. The beds are quartzites, and shales or schists, with thick 

 banket reefs. The principal reason for considering the beds to be 

 more recent than the Witwatersrand series is, that though they are 

 distinctly tilted, the dip is always slight, while the Witwatersrand 

 beds in the Colony are much folded. Unfortunately, there does not 

 appear to be any place where the relationship of the two series can 

 be observed directly, for both at Nondweni and Denny Dalton the 

 Black Reef series lies directly over granite. The rocks in the supposed 

 Black Reef series do not appear to be so much metamorphosed as in 

 the Witwatersrand series, but that might be accounted for, apart from 

 the difference in age, by the smaller amount of folding. The series at 

 Denny Dalton is undoubtedly older than the Table Mountain sand- 

 stones, for the Table Mountain sandstones, at a higher level in the 

 Entonjaneni hills near by, are only very slightly metamorphosed, and 

 lie horizontally. Dwyka conglomerate lies directly over the Black 

 Reef series near Nondweni, Denny Dalton and Ulundi. 



The bankets appear to be coarse with little secondary silica. 

 They are low grade except in portions of the reef in the Denny 

 Dalton Mine. 



Gold in Table Mountain Sandstones. — The Table Mountain 

 sandstones are well developed in Natal on the coast side of a 

 line running from the centre of Alfred County to Ulundi, in 

 Zululand. In Alfred County they are white, friable sandstones, 

 closelv resembling the coal measures in appearances, but 

 distinguished from them by the presence of overlying dwyka. Near 

 Umzinto they become red and hard, owing to the presence of a 

 silicious cement, becoming soft and friable again in Zululand, though 

 still in great part red in colour. Gold is widely distributed in small 

 quantities, but the place at which most is known of its occurrence is 

 in Victoria County, near Chaka's Kraal and Stanger. The gold 

 occurs in almost vertical quartz reefs, apparently following lines of 

 faulting and subsidiary fracturing, and also in interstratified beds 

 of conglomerate and sandstone. The gold-bearing sandstones and 

 conglomerates, where unw^eathered, are pyritic, and the gold is 

 apparently very irregularly distributed in them. 



It is interesting to note that the gold occurs in the sandstone in 

 two forms, viz., coarse, almost cubical and dark in colour, and fine 

 and lighter yellow in colour, resembling the gold from "banket," 

 but with some pieces of wire gold of similar colour. The coarse 

 gold is found in weathered stone, and the fine in unweathered, and 

 there is reason to think that the coarse gold has been formed by 

 secondary action. 



