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ME. PKEDERIC P. MENNELL ON THE 



[Aug. 1 910, 



to recrystallizatioii under pressure, and is not necessarily an indi- 

 cation of the original direction of bedding. Although the rock is 

 always to some extent ferruginous, the iron content may be very 

 low and that of the different layers may vary extremely. Some 

 parts are of a jaspery or chert-like nature, while other portions are 

 nearly pure iron-oxide : usually haematite, but not infrequently 

 magnetite, and occasionally limonite. The series exactly resembles 



Outcrop of ' Banded Ironstone ' in the bed of the Sebakwe River, 

 near the Globe § Phoenix Mine. 





W%$m 



il 



the great iron-bearing group of the Lake Superior region, and may 

 one day be of equal value on account of its metallic contents. Even 

 now its economic importance is by no means inconsiderable, as 

 several of the largest auriferous deposits in the country are impreg- 

 nations in the Banded Ironstone Series. 



If any proofs were needed of the sedimentary origin of these 

 beds, such proofs might be derived from their composition, their 

 widespread and continuous distribution over the country, and their 

 relations with the surrounding rocks. They also occasionally in- 

 clude slaty beds (as, for instance, near Malungwane Hills) ; while, as 



