48 



Ntunerous indeed are the theories relative to the formation 

 and filli ng of veins, &c. ; but this question, as a whole, does not 

 concern us, it being only the ores of Iron that engage our 

 attention, and the general theories relative to Copper, Tin, Lead, 

 and other mineral veins and lodes, do not at all help us; for 

 whUst most if not all of these ores are esoterically derived, the 

 opposite, or exoteric condition, I believe to be the origin of most, 

 if not all, our Iron lodes and deposits. No question is perhaps 

 more difficult to grapple with, and few subjects have been, or 

 are, more fruitful in hypotheses : for where the metallic minerals 

 are derived from is stUl a question — whether directly from 

 repositories below, or esoteric, — or indirectly by segregation or 

 solution in minute particles from the adjacent rocks, or infiltra- 

 tion. It may be that at the time our various minerals were 

 deposited in veins, those veins might have been beneath the 

 sea, and also that they were covered with considerable rock 

 masses, which have since been removed by denudation ; and the 

 veins that are now exposed and worked may have been, therefore, 

 much deeper in the earth at the time the minerals were deposited 

 in them, and both the rocks and the water have had a much 

 higher temperature through deeply seated pressure, as well as 

 chemical and internal heat, than they now possess, or since the 

 denudation of the rocks from above them. Again, the waters 

 may have been in a state of heated vapour, and have acted upon 

 materials just as the frequent occurrence of pure and uncombined 

 Silica, either in the state of crystalline or amorphous Quartz, seems 

 to require the presence of water, probably at high temperature, 

 which, traversing the adjacent rocks, might dissolve some of the 

 SiHcates, and deposit the Silica in an uncombined state. 



The investigations of Sorbt, Dobre, and others, have long 

 led us to believe and understand that many of the CrystalKne 

 rocks are hydato-pyrogene, rather than purely pyrogene, an 

 hypothesis which has for its basis that many of them (Granite, 

 Gneiss, &c.) were formed at high temperatures, but in connection 

 with water. This remarkable discovery, and the results arising 

 from it, is of the highest importance relative to the theory of 

 mineral veins, for in them, and to a large extent, we constantly 



