presidential address section b. 59 



Iron Oxide. 



The material under this heading is used in the manufac- 

 ture of mineral paints, the production of which has become an 

 industry of some importance. 



Iron-Ore — Iron. 



As a result of conditions due to the war South Africa is 

 at last about to enter the ranks of the world's iron producers. 

 Two small blast furnaces are actually on the point of being 

 blown in, and two others are expected to be in operation within 

 the next two or three months ; so that what was considered a 

 few years ago as being without the bounds of commercial prac- 

 ticability will shortly be an accomplished fact. The sedimentary 

 iron ores of the Pretoria series and Karroo system afford the 

 bases of all four ventures. The furnaces already completed are 

 those of the Pretoria Iron Mines, Ltd., and of the Transvaal 

 Blast Furnace Company, Ltd. The former company propose 

 smelting in a 50-feet furnace, with coke prepared from Dundee 

 coal, a mixture of siliceous and " clay-band " ores from the 

 lower portion of the Pretoria series. The siliceous ore, an 

 arenaceous ootltic ironstone,* in which most of the iron is pre- 

 sent as martite, assays from 40 to 54 per cent, of iron, and from 

 14 to 22 per cent, of silica; sulphur and phosphorus being both 

 very low, and titanium present in traces only. The " clay- 

 band " ore assays from 50 to 55 per cent, of iron, from 7 to 9 

 per cent, of silica, and from .5 to .6 per cent, of pho.sphorus. 

 Both types of ore can be very cheaply mined, and are available 

 in enormous quantity, millions of tons of the siliceous ironstone 

 being actually in sight. 



Limestone from Taungs, in Bechuanaland, is to be used 

 as flux. The furnace has a capacity of from 12 to 15 tons of 

 pig iron per diem. 



The Transvaal Blast Furnace Company, who have erected 

 a 50-feet blast furnace at Vereeniging in connection with the 

 Union Steel Corporation, intend smelting a very pure bedded 

 magnetite ore, found in the Transvaal Coal Measures on the 

 farm De Roodepoort, No. 67, 7 miles east of Ermelo. 



x^s there is very little information on record regarding the 

 iron ores of the Transvaal Coal Measures, it may be noted that 

 they occur irregularly interstratified with the almost horizontal 

 sandstones of the Ecca series in Ermelo and Middelburg dis- 

 tricts, t The beds are up to 6 feet in thickness — the average 

 thickness being about 18 inches — and occur at varying distances 

 above the coal seams, sometimes resting directly on them. They 

 are in the form of attenuated lenses and consequently imper- 



* CA Wagner. P. A,, and Stanley, G. H. : S.A. Min. Journ. (1917), 

 /uly 14 and 28, and August 4 and 18. 



t Cf- Henderson, J. McC. : Proc. Geol. Soc. S.A. (1909). 21. 



