ORIGIN AND DEVELOPMENT OF ORE-DEPOSITS. 333 



have effected ; and that hence, many anomalies may have arisen, 

 especially in relation to tin. 



1 1. That the electrical re-action of the different metalliferous 

 bodies, and of masses of ore on each other after their deposition 

 in the fissures, may have corrected such anomalies in some 

 instances, and that they may have given rise to them in others, 

 by changing the direction of the electric currents and modifying 

 the relative positions of the deposits ; and that the pseudo- 

 morphous crystals of various descriptions, as well as other 

 phenomena observable in mines, fully prove that some such 

 secondary action must have taken place. 



12. That cross-veins may have been filled mechanically, or 

 by the deposition of silica from a state of solution, or by both 

 these means ; and that the striated and radiated structure 

 of the quartz, may be owing to the tendency of electricity, under 

 ordinary circumstances to pass transversely rather than longi- 

 tudinally through north and south veins. 



13. That assuming the proofs of the progressive opening 

 and filling of lodes and cross-veins to be admitted, it seems to 

 follow that many intersections may have been caused by the more 

 ready accumulation of clay and other mechanical matter, and 

 even of silica from its solution, than of the more slowly-formed 

 metalliferous or crystalline deposits. 



14. That the frequent occurrence of a mass of ore in that 

 part of a lode which is intersected by a cross-vein ; and also of 

 small branches of ore, from a dislocated part of a lode on one 

 side of a cross-vein without there being corresponding veins near 

 the other part of the lode on the opposite side of the cross- vein, 

 afford strong evidence of the deposition of the ore in such cases 

 after the intersection took place, and that it was accumulated in 

 the E.W. vein, rather than the N.S. one, by the influence of 

 electro-magnetism. 



15. That the small veins of copper and tin ore which are 

 often found in cross-veins between the dislocated parts of lodes, 

 and the frequent occurrence of more considerable, and yet for the 

 most part very limited, quantities of these ores in the former 

 in the immediate vicinity of intersections, are additional argu- 

 ments in favour of the operations of the same definite agency. 



