194 NEW YORK STATE MUSEUM 



agreement as to which is primary and which secondary, some 

 investigators regarding the oxide as derived from a primary silicate 

 and others regarding the relation as just the reverse while in both 

 cases various views are held as to the conditions of formation of 

 the original mineral. 



For example: while Beck 1 gives the impression that chamosite 

 and thuringite are primary precipitates, Zalinski 2 considers them 

 secondary after deposits of indeterminate nature. Van Werweke 3 

 in his important contribution to the geology of the Minette ores, 

 concludes that they were originally precipitated, in part, as ferrous 

 silicate which was subsequently altered to oxide. 



In the case of similar ores in Germany, on the other hand, Lepsius 4 

 and Gaub 5 regard the limoni'te as the primary precipitate and the 

 silicate as formed from it by secondary processes. 



More extended references would give further evidence of this 

 diversity of view. 



Another solution of the silicate problem for the Clinton ores was 

 offered some years ago by McCallie 6 who, finding scales of a green 

 mineral in the Clinton ores of Georgia and noting that some ferrous 

 iron was reported in analyses, suggested that both phenomena 

 indicated the presence of glaucoriite, and concluded that the Clinton 

 ores were originally deposited as glauconite and subsequently altered 

 to hematite. Such an explanation of the ores is exceedingly 

 attractive, particularly because it connects them with deposits now 

 forming over extensive areas of the sea bottom; although it must 

 be said that geological evidence points to distinctly shallower water 

 conditions for the Clinton ores than those under which glauconite 

 is now forming. 



But, as was pointed out in the paper on Types of Ore Deposits, 

 there are other and more serious objections to this hypothesis, 

 and the evidence presented in the foregoing pages argues most 

 strongly against it, leading to the conclusion that the green mineral 

 of the Clinton ores is not glauconite, but chamosite or a related 



1 Beck, R., The Nature of Ore Deposits, p. 84-85, 1905. 



2 Op. cit., p. 81-84. 



3 Van Werweke, L., Zusammensetzung u. Entstehung der Lothringisch-luxem- 

 burgischen oolitischen Eisenerze (Minetten). Oberrhein Geol. Verein., Separat- 

 abdruck, April, 1900. 



4 Lepsius, R., Geol. von Deutschland, 2 Lief. I, p. 219, 1903. 



5 Gaub, F., Die Jurassischen Oolite der Schwabischen Alb. Neues Jahrbuch 

 f. Min. etc., 1908, II, p. 94. 



6 Op. cit., p. 185-94. 



