On Mineral and Metallic Veins. 



483 



times found in the copper veins, and as other metallic veins 

 w^hich deviate from the E, and W. course, contain increasing 

 quantities of clay, and the flucan veins which run N. and S. are 

 filled with clay, an opinion has obtained with many, that tin and 

 copper are older metals than the rest, and that tin, for these 

 reasons, and on account of its being found in granite, is the oldest 

 of all the metals. If this priority of age in metals were true, it 

 would be a fair subject for adventure in countries where tin has 

 not yet been found — and that is the case in the U. S. — to work 

 through a bad copper mine in order to convert it into a good tin 

 one. With our present information, we do not see any positive 

 proofs of priority of age in metals, especially from their presence 

 in particular formations. When a vein is continuous through 

 primary and secondary rocks, it is evident that these last had 

 been deposited before the vein had penetrated the first. It is 

 true, tin has not been found in secondary rocks; it is found, 

 however, in slate, and therefore the circumstance of its being 

 found in granite is not to be adduced as a proof of its priority 

 of age ; for the cases of its limitation to the granite may be ac- 

 counted for, by supposing that the power which produced the 

 fissure, only operated upon the granite. If metallic veins, in their 

 origin, are analogous to trap dykes, or veins, then we see no limita- 

 tion to the extent of tin veins, but in the nature of the ^ 

 power which produced them, and in the absel 

 condary rocks, to be affected by it. In the case of the great Cleve- 

 land dyke, we find the trap penetrating even through the coal 

 beds ; but tin, we believe, has not yet been found in rocks actually 

 subjacent to the secondary rocks. We think this a sufficient 

 reason why tin is usually found limited to granite and slate. 



Pleased as we always are at seeing a new direction given 

 to inquiries of this nature, yet we have thought that super- 

 fluous pains have been taken by European writers, to turn 

 opinions from the igneous origin of metallic veins. The ancient 

 Wernerian notion, that minerals and metals settled into fis- 

 sures, from aqueous solution, has no friends among enlightened 

 geologists of the present day : how their contents got exclusively 

 into fissures, at great distances from each other, having a very 

 irregular inclination, sometimes extremely dilated, then con- 

 tracted into a very small space, and afterwards dilated again, 

 resembling a number of blown bladders, connected by a long 



