522 tyler. SEDIMENTARY IRON DEPOSITS [Ch. 28 



ites have been studied very extensively, Reiche (1945, p. 66) states that 

 ". . . concepts of weathering under tropical conditions are apparently 

 in a state of discouraging confusion." Additional research is also 

 needed to explain the localization of the oxidation and leaching that 

 resulted in the formation of the ores of the Lake Superior region. 

 Studies of this type may lead to the discovery of new, high-grade de- 

 posits. 



Further research is also needed on the mineral composition of sedi- 

 mentary iron deposits to ascertain the manner of occurrence and dis- 

 tribution of phosphorus, sulphur, nickel, and other elements deleterious 

 to the economic use of the material. Furthermore, as depletion of the 

 higher grade iron deposits necessitates the use of lower grade materials, 

 beneficiation becomes of more immediate importance. A more thorough 

 knowledge of the mineral composition and texture of the iron-bearing 

 and associated gangue minerals is a necessary prerequisite to ore- 

 dressing problems. 



REFERENCES 



* Allen, E. T., Crenshaw, J. L., and Johnston, J. (1912). The mineral sulphides 

 of iron: Amer. Jour. Set., vol. 33, pp. 169-236. 



* Ailing, H. L. (1947). Diagenesis of the Clinton hematite ores of New York: 

 Bull. Geol. Soc. Amer., vol. 58, pp. 991-1018. 



Cayeux, L. (1909). Les minerals de }er oolithique de France, I, Minerals de jer 



primaires: Imprimerie Nationale, Paris, p. 284. 

 Crane, G. W. (1912). The iron ores of Missouri: Mo. Bur. Geol. Miner., 2nd ser., 



vol. 10, pp. 111-112, 127-129. 

 Eckel, E. C. (1914). Iron Ores: McGraw-Hill Book Co., New York, p. 56. 

 Galliher, E. W. (1935). Glauconite genesis: Bull. Geol. Soc. Amer., vol. 46, pp. 



1351-1366. 

 Griffen, P. H. (1892). The manufacture of charcoal iron from the bog and lake 



ores of Three Rivers district, Province of Quebec, Canada: Trans. Amer. Inst. 



Min. Engrs., vol. 21, pp. 974-992. 

 Gruner, J. W. (1922). The origin of sedimentary iron formations; the Biwabik 



formation of the Mesabi range: Econ. Geol., vol. 17, pp. 407-460. 

 (1937). Hydrothermal leaching of iron ores of the Lake Superior type: 



Econ. Geol, vol. 32, pp. 121-130. 

 Hadding, A. (1929). The pre-Quaternary rocks of Sweden, III, Paleozoic and 



Mesozoic sandstones of Sweden: Lunds Universitets Arsskrijt, vol. 25, No. 3, 



p. 236. 

 * (1932). The pre-Quaternary rocks of Sweden, IV, Glauconite and glau- 



conitic rocks: Lunds Universitets Arsskrijt, vol. 28, No. 2, pp. 44-54. 



* Harder, E. C. (1919). Iron-depositing bacteria and their geologic relations: 



U. S. Geol. Survey, Prof. Paper 113, pp. 41, 77. 

 Hawley, J. E., and Beavan, A. P. (1934). Mineralogy and genesis of the Mayville 

 iron ore of Wisconsin: Amer. Min., vol. 19, pp. 493-514. 



* Articles of more general interest. 



