120 A SOUTfi AFRICAN IRON INDUSTRY. 



ores occur in large and workable quantities, one being- the Pre- 

 toria district, and the other near Alaritzburg. 



In the former place there are two beds of siliceous ore 

 A-arying in thickness from 4 to 20 feet, and extending for many 

 miles : one small range alone, south of Pretoria, which can be 

 mined by open-cut and adits, being estimated to contain over 

 4,000,000 tons of ore, assaying 45 j)er cent, or over in iron. 



Analyses by the author are as follows : — 



per ])er per per per 



cent. cent. cent. cent. cent. 



Silica (SiOa) ... 14.30 17.^3 22.1 17.44 21.96 



Ferric oxide (FAJ 76.93 73.81 63.75 69.43 65.57 



Alumina (AKO,) 7.20 7.31 10.41 7.38 6.54 



Lime (CaO) . . . . undet. undet .62 .75 1.20 



Magnesia (MgO) undet. undet. undet. .47 .44 



Sulphur .03 .03 undet. .014 .014 



Phosphorus .... .14 .17 undet. .17 .24 



Tron 53.9 51.8 44.6 48.6 45.9 



There is also a persistent bed of " clay-band " ore, which 

 outcrops for several miles. It is not so thick as the siliceous ore 

 — about two feet — but is richer in iron, assaying about 50 per 

 cent. An analysis by the author is as follows : — 



per cent. 



Silica 7.70 



Ferric oxide 73-57 



Alumina 7 94 



Lime .45 



Magnesia - .33 



Sulphur .029 



Phosphorus .52 



Iron 51-5 



By mixing this with the siliceous ore, the amount of lime- 

 stone flux required is very considerably reduced, and not more 

 than 15 per cent, to 25 per cent would be necessary. 



Samples from the Maritzburg district assayed by the author 

 showed from 40 to 5r.5per cent. iron. 



These occurrences" were reported on by Dr. Hatch, for the 

 Natal Government in 1909, and in his report* several analyses 

 are given which show that this ore is a hydrated hematite com- 

 paratively low in silica — usually about 5 to 10 per cent. — and 

 assaying 45 to 60 per cent. iron. 



Little work had then been done in opening up the deposits, 

 and he was not convinced that workable quantities existed. I 

 am informed, however, that since his visit some prospecting work 

 has been done, and the beds found to exist over a large area, of 

 thickness from 2 to 5 feet, and outcropping for 30 miles. 



*Rcport on Mines and Mineral Resources of Natal : F. H. Hatch 

 TroTo). 



