RBPORT ON MINERAL VEINS. 9 



5. To have determined the essential differences that are 

 found between the structure of veins and that of beds. 



Werner illustrates his propositions by many observations, 

 which his intimate acquaintance with the extensive mining di- 

 stricts in which he was engaged gave him the power of observing 

 and recording ; and it must be conceded, at least, that his state- 

 ment of facts, and his arrangement of them, give him a manifest 

 superiority over most writers upon this subject. Every one 

 who has had opportunity to see much of these storehouses of 

 nature will be struck with the accuracy of most of his descrip- 

 tions, whether they admit the theory by which they are ex- 

 plained, or not. 



He allows that the enrichment of veins, or their being filled 

 with ores or metals, may have taken place by, 



1. «. A particular filling up from above. 



b. By particular internal canals. 



c. By infiltration across the mass of the vein. 



2. A metallic vein may be increased by the junction of a new 

 metalliferous vein. 



3. Though rarely, the richness of a vein may be the effect of 

 an elective attraction or affinity of the neighbouring rock. 



The mode assigned by Werner for the formation of the 

 spaces now occupied by veins is still further demonstrated, in 

 his opinion, by the relation which veins have to one another ; as. 

 Their intersecting one another. 

 Their shifting one another. 

 Their splitting one another into branches. 

 Their joining and accompanying one another. 

 Their cutting off one another. 

 All these peculiarities, he remarks, are produced by the ef- 

 fects of a new fissure upon one that is older. 



Subsidence having been the cause of fissures he thinks is 

 proved by the difference in the level in the parts of the same 

 stratum or bed in which a vein is inclosed ; and this throwing 

 up or down, as the miners term it, bears a proportion to the 

 size of the vein. 



The interior structure of many veins is quoted to show that 

 the fissures had been originally open, and which had been af- 

 terwards filled by degrees. 



Such veins are composed of beds, arranged in a direction pa- 

 rallel to their sides ; their crystallizations are supposed to show 

 these beds to have been deposited successively on each other, 

 and that those next the walls have been first formed. A cir- 

 cumstance much relied on, also, is the existence of rolled masses 

 or water-borne stones, fragments of the adjacent rock, some- 



