I9I4.] CONCEPTION AND TRINITY BAYS, NEWFOUNDLAND. 453 



the process is quite like the serpentinization of olivine but differs 

 essentially from the latter alteration in the fact that the secondary 

 mineral, chlorite, derives none of its material from the original 

 mineral, barite, its change involving a complete replacement by 

 wholly new material. It is a marked example of the comparative 

 ease with which substances which, like barium sulphate are regarded 

 in the laboratory as very stable, yield to the attack of natural 

 reagents. 



This replacement seems to have accompanied a more or less 

 general chloritization of the whole formation, at a period long sub- 

 sequent to the concentration of the manganese ore and under totally 

 different conditions. 



Phosphate. — Tri-calcium phosphate, Ca3(P04)2 also is a very 

 conspicuous accessory of the manganese deposits of Newfoundland, 

 averaging, for those beds of which analyses were made, about 6.0 

 per cent, and for the phosphatic nodules of the nodular bed over- 

 lying the manganese zone at Manuels, 38.77 per cent. When we 

 stop to consider the amount of phosphorus in the lithosphere as .11 

 per cent. (Clark, 2: 32) the amount of concentration in these 

 deposits, particularly in the nodules, becomes very noticeable and 

 something of great interest. The similarity in chemical composi- 

 • tion of the phosphatic nodules of Manuels brook and those of Han- 

 ford brook, N. B., has been referred to on page 409. As the writer 

 has been unable to make as thorough a study of these nodules as he 

 would have liked, it is hoped that at some future time the investiga- 

 tion may be continued. At this time then a very brief resume of 

 the modes of concentration of phosphorus may be of interest be- 

 cause of apparent application to the deposit under consideration. 



According to De Launay (5: 646) there are three stages in the 

 concentration of phosphatic deposits, namely solution of calcium 

 phosphate, in which he considers that in surface conditions 



" the constant presence of carbonic acid and sodium chloride or chlorhydrate 

 of ammonia in the waters determines the sohition of phosphate." 



The second stage is that in which organisms play an important role. 



