208 Dr. Mac CuUoch on Mineral Veins. 



The metallic minerals, thus found, are the following : 



Copper. Sphene. 



Oxydulous iron. Iron pyrites. 



Galena. Oxyde of Tin. 



Graphite. Sulphuret of molybdena. 

 Chromat of iron. 



Such is the balance, as far as it yet appears possible to 

 construct a tolerable list of this nature, between the aqueous 

 and the igneous minerals. It would be highly improper, in the 

 present state of things, to deduce from it any thing respecting 

 a theory of mineral veins. For, though all the minerals of 

 these were aqueous, or all igneous, we are equally at a loss to 

 conjecture whence they came, and how they are so limited and 

 so disposed as they are in veins. It might indeed be consi- 

 dered an argument in favour of an igneous theory, that the 

 mines of Nagyag lie in volcanic rocks. But it is evident that 

 this fact proves no more in this case than in that of granite or 

 trap ; since, in all of these rocks alike, aqueous infiltration 

 takes place, as well into the veins as into the volcanic and 

 trap amygdaloids. 



But it is here worthy of remark, that of the earthy minerals 

 actually found in mineral veins, there are more of an aqueous 

 than of an igneous origin ; although there are many more 

 igneous than aqueous minerals in nature. With respect to the 

 metallic ones, the ditTerencc is still more in favour of the 

 aqueous minerals. That many of both kinds have a double 



