362 EEPOKT OF NATIONAL MUSEUM, 1899. 



not infrequently of a thickness such as to cause their origin as above 

 stated to seem well-nig-h incredible were there not sufficient data 

 acquired within historic times to demonstrate its accuracy beyond dis- 

 pute. Thus it is said^ that in the j^ear 1840 a vessel loaded with 

 guano on the island of Ichabo, on the east coast of Africa. During 

 the excavations which were necessary the crew exhumed the dead body 

 of a Portuguese sailor, who, according to the headboard on which his 

 name and date of burial had been carved with a knife, had been interred 

 fifty-two years previously. The top of this headboard projected 2 feet 

 above the original surface, but had been covered by exactly 7 feet of 

 subsequent deposit of guano. That is to say, the deposition was going 

 on at the rate of a little over an inch and a half yearly. 



LOCALITIES OF PHOSPHATES. 



Cajiada.^According to Dr. Ells, of the Canadian Survey,^ the dis- 

 covery of apatite in the Laurentian rocks of eastern Canada was first 

 made in the vicinity of the Lievre by Lieutenant Ingall in 1829, though 

 it was not until early in 1860 that actual mining was begun. The 

 mineral occurs in the form of well-defined crystals in a matrix of 

 coarsely crystalline calcite (Specimen No. 67942, U.S.N.M.) and in 

 vein-like and pockety granular masses along the line of contact 

 between eruptive pyroxenites and Laurentian gneisses. The first 

 form is the predominant one for Ontario onl}", the second for Quebec. 

 From a series of openings made at the North Star Mine, in the region 

 north of Ottawa, it appears that the massive coarsely crystalline gran- 

 ular apatite follows a somewhat regular course in the pyroxenite near 

 the gneiss, but occurs principally in a series of large bunches or chim- 

 neys connected with each other by smaller strings or leaders. Some- 

 times these pockety bunches of ore are of irregular shape and yield 

 hundreds of tons, but present none of the characteristics of veins, 

 either in the presence of hanging or foot walls, while many of the 

 masses of apatite appear to be completely isolated in the mass of 

 pyroxene, though possibly there may have been a connection through 

 small fissures with other deposits. The lack of any connection between 

 these massive apatites' and the regularl}'^ stratified gneiss is evident, 

 and their occurrence in the pyroxene is further evidence in support of 

 the view that these workable deposits are not of organic origin, but 

 confined entirely to igneous rocks. In certain cases where a supposed 

 true-vein structure has been found, such structure can be explained 

 by noticing that the deposits of phosphates occur, for the most part at 

 least, near the line of contact between the pyroxene and the gneiss. 



By far the greater part of the Canadian apatite thus far mined has 

 been from the Ottawa district of Quebec, where it is mined or quar- 

 ried mainly from open cuts and shafts. The principal fields lie in 



1 R. Ridgway, Science, XXI, 1893, p. 360. 



^ The Canadian Mining and Meclianical Review, March, 1893. 



