Origin of Quartz and Metalliferous Veins. 221 



richness of the metalliferous veins at the points of intersec- 

 tion, &c., by assuming the melted condition of the penetrating 

 vein-masses. If melted masses did ascend through vein-lis- 

 sures which traversed various formations, it is not possible 

 to understand how certain substances could accumulate be- 

 tween some rocks, and different ones between others. The 

 veins of granite, porphyry, and basalt, which so frequently 

 traverse various formations, and in regard to which we can 

 only assume an igneous origin, exhibit no qualitative distinc- 

 tion in these different formations. A granite vein remains 

 the same, whether it pass through granite and mica-slate, or 

 granite and clay-slate, &c. 



The penetration of the adjacent rock by ores in the melted 

 condition can, as has been above noticed in reference to the 

 penetration of melted masses into compact rocks, just as 

 little be explained. Moreover, it cannot be understood how 

 a decomposition of the adjoining rock could thus be produced, 

 and it can just be as little understood how this decomposi- 

 tion could be effected by a subsequent introduction of water, 

 inasmuch as the rocks must have been rendered more com- 

 pact and more impervious to water by means of the pene- 

 trating ores. 



Nor can it be at all understood how a melted mass, which 

 had ascended through a fissure that traversed the vein-mass 

 of another fissure, could have produced an enriching effect on 

 the point of intersection ; whether we imagine that the last 

 vein-mass was already solidified, or that a simultaneous 

 rising of fused masses took place in both fissures. 



Lastly, the principle announced by Schmidt,* and one 

 which is confirmed by a multitude of facts, viz., " that the 

 formation of one and the same vein-fissure took place very 

 gradually, and occupied a long period of time ; and that, from 

 the commencement, the filling of that fissure progressed si- 

 multaneously with this successive opening and widening of 

 the fissure," can only be reconciled with the opinion, that the 

 filling of the vein-fissures took place in the moist way. 



Water could penetrate the narrowest fissures, and could 



• Karsten's Archiv, vol. xvii., p. 85. 



