The Apatite Deposits oj Canada. (39 



dred tons of apatite, I found to intersect, in a nearly horizontal 

 attitude, vertical strata of gneiss ; and in rare cases what appear, 

 from their structure and composition, to be veins, are found coin- 

 ciding in clip and in strike with the inclosing strata. 



The distinction between the beds and the veins of apatite is one 

 of considerable practical importance, — first, as related to the 

 quality of the mineral contained, and second, as to the continuity 

 of the deposits. The apatite of the interbedded deposits is gen- 

 erally compactly crystalline, and free from admixtures, although 

 in some cases including pyrites, and more rarely magnetic iron-ore, 

 with which it may form interstratified layers. Many will recall 

 in this connection the band of magnetite, with an admixture of 

 granular apatite, found interstratified in parts of the great magnetic 

 ore-deposit known as the Port Henry mine, near Lake Champlain, 

 in Essex county, New York ; where in certain layers formerly 

 mined, the apatite made up about one-half the bulk. I have 

 seen an example of a similar association of magnetite and apatite 

 from Frontenac county, Ontario. The latter mineral is, however 

 for the most part found included in the beds of pyroxene rock, 

 already mentioned, which is generally pale green or grayish green 

 in color, sometimes containing quartz and orthoclase, and dis- 

 tinctly gneissoid in structure. 



The veins present more complex conditions ; while they are 

 often filled throughout their width by apatite as pure and as 

 massive as that found in the beds, it happens not unfrequently 

 that portions of such veins consist of coarsely crystalline sparry 

 calcite, generally reddish in tint, holding more or less apatite in 

 large or small crystals, generally with rounded angles, and often 

 accompanied by crystals of mica, and sometimes of pyroxene md 

 other minerals. Occasionally these mixtures, in which the carbon- 

 ate of lime generally predominates, will occupy the whole breadth 

 of the vein. These limt-veins, as they are called by the miners 

 sometimes include cavities from which the carbonate appears to 

 have been dissolved by infiltrating waters, leaving free the in- 

 closed crystals of apatite. In some cases, however, these veins 

 present cavities which have apparently never been filled with solid 

 matter, and exhibit drusy surfaces, with quartz, and more rarely 

 with barytine and zeolites. The calcareous veins often carry so 

 much carbonate of lime as to be valueless for commercial purpos- 



