384 ON MINERAL VEINS. 



because it occurs in secondary limestone. I need not 

 enumerate all the particulars contained in this un- 

 founded assertion; while a few simple facts will anni- 

 hilate the whole system. Cobalt occurs in granite, 

 in many of the primary schists, and in the secondary 

 sandstones. Copper has been found throughout the 

 whole system, from granite up to Trap, inclusive. 

 Lead is found alike iu the primary and secondary 

 strata, and Iron is universal. This short list of ex- 

 ceptions already overwhelms the rule. If, again, the 

 nature, or imagined age of the rock which is traversed 

 by a vein is to be made the criterion of the age of the 

 latter, or of the included minerals, it must be remem- 

 bered that a vein must traverse every rock that was 

 in existence at the time of its formation. The vein 

 that intersects the granite, intersects the superincum- 

 bent strata also; and tin, copper, or lead, as it may 

 happen, will occur in every part of it. It may have 

 required uncounted centuries to form all the strata, 

 but the vein is, comparatively, the work of a moment. 

 To attempt to classify metallic veins according to 

 certain imaginary dates of formation, is to make 

 systems which, except at Freyberg, philosophy dis- 

 claims. If there were a hundred, instead of ten or 

 sixteen " lead-glance formations" we must be content 

 to remain ignorant of the ages of all that we can- 

 not prove by the uncontrovertible marks already 

 indicated. 



There is not one circumstance in the history of 

 veins, whether we regard their forms, positions, seats, 

 origins, or the nature and disposition of the minerals 

 they contain, which can entitle us to conclude that 

 they possess a resemblance or analogy throughout 

 the world, that they are of definite and definable 

 ages, or that they are in any sense of the word, general 



