The Phosphates of America. 39 



thickness. Several large parallel bands of apatite occur here with 

 intervening layers of pyroxene and feldspathic rock, across a 

 breadth of at least 250 feet of veinstone, besides numerous small 

 irregular, lenticular masses of apatite. The pyroxenite in this 

 lode, as elsewhere, includes in places large crystals of phlogopite, 

 and also presents in drusy cavities crystals of a scapolite and 

 occasionally small, brilliant crystals of colorless chabazite, which 

 are implanted on quartz. 



At the Little Rapids mine, not far from the last, where well- 

 defined bands or layers of apatite, often eight or ten feet wide, 

 have been followed for considerable distances along the strike, and 

 in one place to about 200 feet in depth, these are, nevertheless, 

 seen to be subordinate to one great vein, similar in composition to 

 those just described, and including bands of granular quartz. ' In 

 some portions of this lode the alternations of granular pyroxenite, 

 quartzite and a quartzo-feldspathic rock with little lenticular 

 masses of apatite are repeated two or three times in a breadth of 

 twelve inches. 



The whole of the observations thus .set forth serve to show the 

 existence, in the midst of a more ancient gneissic series, of great 

 deposits, stratiform in character, complex and varied in composi- 

 tion, and though distinct therefrom, lithologically somewhat simi- 

 lar to the enclosing gneiss. Their relations to the latter, however, 

 as shown by the outlines at the surfaces of contact by the included 

 masses of the wall-rock, the alternations and alternate deposition 

 of mineral species and the occasional unfilled cavities lined with 

 crystals, forbid us to entertain the notion that they have been filled 

 Tyy igneous injection, as conceived by Plutonists, and lead to the 

 conclusion that they have been gradually deposited from aqueous 

 solutions. 



As one of the most interesting results of the extensive and 

 costly mining operations carried out during the past few years, it 

 has, we repeat, been demonstrated that the apatite really does 

 traverse the entire stratum in which it is found, and that, if it is 

 extremely pockety and deceptive in its occurrence, it nevertheless is 

 perfectly persistent. It has also been proved that, to put it broadly, 

 the same geological characteristics prevail throughout the belts. 



It hence follows that all the deposits may be mined by the same 

 method, and that, since we are called upon to deal with invariably 

 mixed-up lodes, the quantity of apatite produced will be in direct 

 proportion to the amount of rock removed. 



