8 S. P. EMMONS — THEORIES OP ORE DEPOSITION 



views, but he was in doubt whether the metals were contained in the 

 rocks as such, or whether the solvents possessed the power of turning the 

 substances they encountered in one place into lead and in another into 

 silver or some other metal. 



Of more permanent value were the works of Von Oppell (1749) and 

 de Charpentier (1778), who were successively directors of the Saxon 

 mines previous to Werner. 



Von Oppell was the first to distinguish bedded deposits (lager gauge), 

 or those which lie parallel with the stratification, from true veins. He 

 also gave to the small branches from a main vein the name of " stringers " 

 (trummer), and noted that veins sometimes shift or fault the strata they 

 cross, in which case he calls them " shifters " (wechsel). He laid stress 

 on the importance of the causes which have produced rents or fissures 

 in the earth, and shows how in the formation of mountains the rocks, 

 being exposed to great desiccation and violent shocks, might split one 

 from another, thus producing rents with some open spaces, which being 

 afterward filled, would form mineral veins. " Where a vein has been cut 

 or deranged by a visible rent," he remarks, " it is again to be met with 

 by following the direction of this last." 



Charpentier was a careful observer and a very cautious theorizer. He 

 says, " Natural history will always gain more from true and accurate 

 descriptions of her phenomena than from many and yet too early ex- 

 planations offered for them " — a most excellent principle which he 

 admirably carries out in his own work. He presents many arguments 

 derived from his own extensive observations in mines against the preva- 

 lent theory that veins were once open cracks formed by contraction, and 

 that they had been filled by material flowing in from the surrounding 

 rocks and hardening in them. Some of his objections were: 



That contraction could not have made the kind of fissures that the 

 veins are found to fill. 



Open or empty spaces could not have existed under the conditions 

 present when they were formed ; pressure would have closed them. 



The fragments of country rock as found in veins could not thus be 

 accounted for. If they had simply fallen into an open crack, they would 

 have accumulated at its bottom. 



The comparatively uniform arrangement of ore in the vein; the en- 

 richment caused by the crossing of one vein by another ; the transition 

 from vein material to country rock, etcetera, could not be explained on 

 the contraction theory. 



Having given his reasons why he believes that veins are not the filling 

 of wide open spaces in the rocks, he says his readers will naturally ask 

 how he supposes them to have been formed, and although he is not 



