442 THE CANADIAN NATURALIST. [Vol. viii 



The apatite-bearing veins bear a certain relation to thegabbro. 

 We must here recall to mind that the apatite-bearing veins 

 occur in a region where gabbro frequently intersects the strata 

 of the primary rocks. All the important deposits of apatite 

 occur either in gabbro or in its immediate vicinity. As the 

 gabbro has suffered far more alteration by the eruption of apatite 

 veins than the other rocks have, perhaps the assumption is jus- 

 tified that the gabbro may have been not perfectly solidified 

 when the veins burst forth. 



The eruption of the apatite-bearing veins occurred either simul- 

 taneously icith or immediately after the outbreak of these gabbro 

 masses. A number of observations would £eem to suggest that 

 the vein masses when they burst out were hydrous aud accom- 

 panied by solutions and gases. "We mentioned that the veinlets 

 of Regardsheien and Ravneberg were sometimes surrounded by 

 as broad a zone of the "spotted gabbro" as the larger veins 

 themselves ; and also that in some cases this zone is broader on 

 one side of the vein than on the other ; farther, that the direc- 

 tion of the small off-shoots is continued by veinlets and stringers 

 of a schistose gabbro inside of the granular " spotted " variety. 

 Finally, we would recall to mind that in several deposits the 

 " spotted gabbro " extends far from the veins. When these con- 

 siderations are all borne in mind, it seems clear that the altera- 

 tion of the gabbro is due only in small part to the heat of the 

 molten veins, but rather to the steam accompanying the erup- 

 tion, which could operate at some distance from the limits of the 

 vein. 



The practical result of our examination is, in brief, that one 

 can reasonably expect to find the apatite in and in the neigh- 

 bourhood- of the gabbro, especially where one or more of its 

 characteristic associates, such as rutile and the frequently de- 

 scribed crystals of green enstatite, are found. As regards the 

 yield of our apatite deposits, it has been found, so far, that 

 only the deposits in the neighbourhood of the gabbro have yielded 

 any considerable output. 



Erratum. — On page 391 line 27, read 14,442 instead of 

 4,442. 



