454 DALE— CAMBRIAN MANGANESE DEPOSITS OF [April 25, 



" The faculty which Uve organisms have of throwing into very dilute solu- 

 tions those substances which to them are necessary and of making them 

 undergo a primary stage of concentration has played a great role for the 

 phosphates." De Launay (5: 646). 



The third stage called by De Launay, " Remises en mouvement " 

 consists in a dissolution of the phosphate contained in preceding 

 deposits which is followed by a reprecipitation of the same upon 

 anything which has served as a center of attraction. The tendency 

 in this mode of concentration is for the phosphate to become more 

 and more like the original apatite in composition, the ultimate source 

 of the phosphorus. It involves both a chemical and a mechanical 

 action, the former in dissolution and reprecipitation and the latter 

 in the formation of nodules which, according to the suggestion of 

 the writer in connection with the manganese nodules of Manuels, 

 may be of physical nature, namely the result of surface tension. 



Iron. — An interesting, and yet problematical, point arises here 

 in connection with the association and separation of iron and man- 

 ganese as related to the manganese deposit under consideration. 

 We should expect, in as much as both elements are taken into solu- 

 tion, that they both might be precipitated together as is sometimes 

 the case with bog ores or, if separated, at no great stratigraphic 

 distance. Because of their different rates of oxidation and dif- 

 ferent degrees of solubility, however, a separation is effected. As- 

 suming both elements entering into solution contemporaneously, the 

 iron would oxidize first, precipitating as Fe^Os, while the manganese, 

 remaining in solution longer, is precipitated either as MnO,, MusOa 

 or MnCOs. Though the Newfoundland manganese deposits con- 

 tain iron, it is much less in proportion to what it would be if both 

 were precipitated together (see Analyses, p. 438) considering the 

 relative abundance of the two elements in the lithosphere referred 

 to on page 447. 



VIII. BIBLIOGRAPHY. 



1. Beck, Dr. R., and Weed, Walter H. 1909. The Nature of Ore Deposits. 



First edition, second impression ; originally published in two volumes. 

 Pp. 1-685. Illustrated. Hill Publishing Co., N. Y. 



2. Clarke, F. W. 191 1. Data of Geochemistry. Bull. No. 380 U. S. G. S., 



pp. 1-782. 



