F. H. Hatch— The Iron Ore Supplies of the Woi^ld. 505 



if the lime is present in excess, be mixed vfiih siliceous ores in the 

 proportion required for a fusible charge. A self-fluxing ore containing 

 25 per cent of iron may be as valuable as, or even more valuable 

 than, a refractory ore containing 35 or 40 per cent. Therein lies 

 the virtue of the calcareous ores of Frodinghani in North Lincolnshire. 



The physical condition of the ore is of the highest importance. 

 If the ore is friable, disintegrates during transportation, and arrives 

 at the smelting works in a dusty condition, or "decrepitates" 

 when heated, it chokes the furnace, prevents the free passage of 

 the gases, and leads to dust losses. Although friable ores can be 

 improved by sintering or nodulizing, this can only be done at the 

 expense of a heavy increase in the cost of production. On the other 

 hand, a hard, dense ore, such as certain classes of magnetite, is 

 refractory, and consequently not looked upon with favour by the 

 ironmaster, except for enriching jDurposes. 



The position of an iron-ore field in regard to the smelting centre 

 has the greatest influence of the utility of the ore. An ore maybe 

 desirable in all other respects, but inaccessibility may prevent its 

 use. A notorious case is Brazil, where vast deposits of the best 

 class of iron-ores remain unworked because of their unfavourable 

 geographical position. 



The first attempt at a census of the iron-ore resources of the 

 world was an inquiry made upon the initiative of the Executive 

 Committee of the International Geological Congress, which met in 

 Stockholm in 1910, and based on the returns obtained from official 

 and non-official geologists all over the world. A summary of the 

 returns from the ^Ye continents made by H. Sjogren showed that the 

 actual known reserves of the world amounted to 22,400 million tons, 

 of which the equivalent iron was estimated to be just over 

 10,000 million tons, or, at the then rate of pig-iron production of 

 60 million tons per annum, insufficient to last for 200 years, without 

 allowing for any increase in consumption. Since 1910 the extension 

 of knowledge by exploratory and development work has led to 

 repeated revisions of Sjogren's figures. 



The principal known iron-ore reserves of the world are those of the 

 Eastern United States, Newfoundland, Cuba, Brazil, Lapland, 

 Spain and the north coast of Africa, the Central European orefield, 

 and the United Kingdom. There are probably also considerable 

 reserves in India, South Africa, Australia, and Canada. 



United Kingdom. 



Of the 15 miUion tons of iron-ore produced in 1918 in the United 

 Kingdom, 80 per cent consisted of Jurassic ironstones, 10 per cent 

 of West Coast low-phosphorus haematite, 8 per cent, of Coal Measure 

 ironstone, and 2 per cent came from miscellaneous sources. 



An estimate of reserves was made by the Geological Survey in 

 1917. Taking the Jurassic ironstones first, the following are the 

 tonnages arrived at for " reserves partially developed ", under the 



