TWENTY-FOURTH ORDINARY MEETING. 299 



tuents of the country rock which they may happen to traverse, such 

 as felspar, quartz, calcite, pyroxene, apatite^ mica, etc., or with some 

 of these minerals mingled together. The gangue adheres strongly to 

 the wall-rock which to a certain distance in is often penetrated by a 

 greater or less proportion of th(^ veinstone. 



All writers on this subject have dwelt on the great irregula]-ity 

 and the puzzling character of the apatite deposits. At first the de- 

 posits were supposed to be beds, but they are now pretty commonly 

 regarded as being rather of the nature of veins of an irregular and 

 unusual nature. Regular veins, generally of small size, filled with 

 apatite or having this mineral as one of the veinstones have also 

 been described by writers on this subject. On the 2nd lot of the 

 third range of the township of Bowman in Ottawa county, I have 

 seen a well defined small isolated vein of pyroxene, cutting gneiss 

 and holding masses of apatite along its centre. The mine at Little 

 Rapids on the Li^vre appears to be in a large vein. These are prob- 

 ably instances of regular veins of very ancient date. But in the 

 great majority of cases the deposits, whether of the pure phosphate 

 or of a mixture of this with other minerals, appear to difier from 

 true fissure veins and to be extremely uncertain and capricious in 

 their forms. 



The mineral is often much mingled with the pyroxenite, but it 

 always has a tendency to form itself into floors and branching veins, 

 having two principal local courses. From an attentive study of 

 these in several of the mines which have been opened in the Li^vre 

 valley, I have come to the conclusion that these lines of deposit mark 

 . approximately the original jointing of the rock. These ancient joints 

 belonged to three sets, two nearly vertical intersecting each other, 

 and one nearly horizontal, analogous to the three sets of dry joints of 

 more recent date, which we usually see in massive rocks at the 

 present day. In the course of the disturbances to which these phos- 

 phate-bearing pyroxenites and gneisses were subjected, the angular 

 masses into which they had been divided by these joints became in 

 places separated and displaced, leaving the spaces which are now 

 filled with the apatite. The process — one of segregation — was 

 , similar to that by which the irregular veins in other varieties of the 

 Laurentian rocks have been tilled with quartz and orthoclase or 

 calcite and its associated minerals. Indeed it has been pointed out 

 that the tribasic phosphate of lime shows an unusually strong ten- 



