THE NONMETALLIC MINERALS. 359 



phatic deposits has been a subiect of much speculation. Their occur- 

 rence under diverse conditions renders it certain that not all can be 

 traced to a common source, but are the result of different agencies 

 acting under the same or different conditions. By many, all forms are 

 regarded as being phosphatic materials from animal life, and owing 

 their present diversity of form to the varying conditions to which 

 they were at the time of formation or have since been subjected. 

 This, however, as long since pointed out, is an uncalled-for hypothesis, 

 since phosphatic matter must have existed prior to the introduction 

 of animal life, and there is no reason to suppose it may not, under proper 

 conditions, have been brought into combination as phosphate of lime 

 without the intervention of life in any of its forms. The almost 

 universal presence of apatite in small and widely disseminated forms 

 in eruptive rocks of all kinds and all ages would seem to declare its 

 independence of animal origin as completely as the pyroxenic, feld- 

 spathic, or quartzose constituents with which it is there associated. 

 The occurrence of certain of the Canadian apatites as noted later, 

 in veins and pockets, sometimes with a banded or concretionary 

 structure and blending gradually into the country rock, is regarded 

 by some as strongly suggestive of an origin by deposition from solu- 

 tion, that is, by a process of segregation of phosphates from the 

 surrounding rock contemporaneously with their metamorphism and 

 crystallization. 



Dr. Ells, of the Canadian survey, would regard those occurring in 

 close juxtaposition with eruptive pyroxenites as due to combination 

 of the phosphoric acid brought up in vapors along the line of contact 

 with the calcareous materials in the already softened gneisses. This 

 explanation as well as others will perhaps be better understood in the 

 part of this work relating to localities. On the other hand, the pres- 

 ence of apatite in crystalline form associated with beds of iron ore, 

 as in northern New York, has been regarded by Prof. W. P. Blake 

 and others as indicative of an organic and sedimentary origin for both 

 minerals. The Norwegian apatite from its association with an erup- 

 tive rock (gabbro) has been regarded as itself of eruptive origin. 



The phosphorites, like the apatites, occur in commercial quantities 

 mainly among the older rocks, and in pockets and veins so situated as 

 to lead to the conclusion that they are secondary products derived by 

 a process of segregation from the inclosing material. Davies regards 

 the Bordeaux phosphorites occurring in the Jurassic limestones of 

 southern France as the result of phosphatic matter deposited on the 

 rocky floor of an Eocene ocean, from water largely impregnated with 

 it. Others have considered them as geyserine ejections, or due to infil- 

 tration of water charged with phosphatic matter derived from the bones 

 in the overlying clays. Stanier, on the other hand, regards the phos- 

 phorites of Portugal as due to segregation of phosphatic matter from 

 the surrounding granite, the solvent being meteoric waters. These 



