IRON 



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Table 58. — Summary description of categories of iron ore 



Average 

 of 

 Subdivision and typical _ _ Present 



location of typical Principal iron minerals iron Form of exploited deposits importance 



example content 



(percent) 



I. Sedimentary deposits 



I-A. Banded iron-formation: 



Labrador Magnetite, hematite, 33 Bed hundreds of feet thick. Major 



siderite, iron silicates. tens of miles in strike length. 



I-B. Ironstone: 



Birmingham, Ala. Limonite, hematite, 30 Beds tens of feet thick, miles in Minor 



siderite, chamosite. strike length. 



I-C. Miscellaneous (bog iron, black band siderite, black sands) : 



Limonite, siderite, >_ Various Negligible 



magnetite, ilmenite. 



II. Deposits related directly to igneous activity 



II-A. Magmatic segregations: 



Kiruna, Sweden Magnetite 65 Tabular bodies, hundreds of feet Modest — 



thick, many thousands of feet 

 long. 

 II-B. Pyrometasomatic deposits: 



Cornwall, Pa. Magnetite, hematite 45 Tabular to podlike deposits, a do 



few hundred feet thick, a few 

 thousands of feet long. 



III. Deposits formed by liydrothermal solutions 



III-A. Replacement deposits in nonferruginous rocks: 



Buena Vista, Nev. Magnetite, hematite, 30 Irregular pods, lenses, stock- Minor 



siderite. works; veins. 



III-B. Enrichments of preexisting ferruginous rocks: 



Minas (Jerais, Brazil Specular hematite, 68 Tabular bodies parallel or sub- Modest 



minor magnetite. parallel to bedding of enclosing 



iron-formation. Thickness up to 

 several hundred feet. 



IV. Deposits produced by surface or near-surface enrichment 



IV-A. Laterite: 



Cuba Limonite, hematite 45 Blankets tens of feet thick, tens Minor 



or hundreds of square miles 

 in area. 

 IV-B. Secondary enrichments of low-grade iron deposits: 



Lake Superior (direct- Limonite, hematite 55 Blankets to sacklike bodies. Major 



shipping and wash dimensions in hundreds to 



ores). thousands of feet. Most 



restricted to depth of a few 

 hundred feet below surface, 

 but Lake Superior deposits 

 extend to several thousand 

 feet 



Resource potential 



Enormous Enormous. 



Medium Large. 



Small Small. 



Medium Medium. 



Small Small. 



Negligible -- Medium. 



Small Large. 



Table 59. — World iron-ore resources, in millions of metric 

 tons, figures rounded {United Nations, 1970) 



Country, region. Identified resources, ^ 



or continent Reserves ^ including reserves 



United States 9,000 101,000 



North America exclusive of 



United States (mostly 



Canada) 36,000 126,000 



South America 34,000 94,000 



Europe 21,000 34,000 



Africa 7,000 31,000 



Australia and 



New Zealand 17,000 =17,000+ 



Asia 17,000 72,000 



U.S.S.R. 111,000 304,000 



Total 252,000 779,000 + 



1 Reserves : Identified deposits from which minerals can be extracted 

 profitably with existing technology and under present economic condi- 

 tions. 



^ Identified Resources : Specific, identified mineral deposits that may or 

 may not be evaluated as to extent and grade, and whose contained minerals 

 may or may not be profitably recoverable with existing technology and 

 economic conditions. 



3 Mostly high-grade ores; vastly greater quantities of lower grade iron- 

 formations are known but have not been assessed. 



The amounts listed as reserves include large 

 quantities of low-grade ores as well as high-grade 

 ores. Therefore the tonnages listed for the various 



continents or regions are not directly comparable in 

 terms of iron content. Nevertheless, the total re- 

 serve figures, even reduced by two-thirds to com- 

 pensate for a ratio as low as 3 tons of crude ore to 

 1 ton of shipping-grade concentrate from taconite 

 ores, represent more than 100 years' supply at re- 

 cent world iron-ore production rates of nearly 750 

 million tons per year. The total crude-ore resources, 

 including reserves, represent more than 300 times 

 the recent annual production of shipping-grade ore. 

 At least four nations in the world — U.S.S.R., 

 Canada, Brazil, and Australia — have ore reserves 

 in excess of 10 billion tons each. Nine — United 

 States, India, France, Peoples Republic of China, 

 Sweden, United Kingdom, Federal Republic of Ger- 

 many, South Africa, and Venezuela — have reserves 

 of more than 1 billion tons each. Other nations 

 which have substantial iron-ore reserves in produc- 

 tion and which have exported more than 500,000 

 tons a year in recent years are Angola, Chile, Korea 

 (south), Liberia, Malaysia, Morocco, Norway, Peru, 



