258 



/ 



ILLUSTRATIONS OF THE 



pofition from water. There is another 



theory 



maintained by fome of the Neptunifts, that the 

 metals in veins were introduced there by infil 



tration *. 



T 



op 



is fufficiently refuted 



by the fad, that rarely any metallic ore is found 



5 vein, or in the rock on either fide of 



it, 



f the V 

 id leafl 



f all 



here the vein is richeft 



This is inconlift 



ith th 



f th 



being carried into the vein by water percolating 

 through the adjacent rocks, unlefs fome fatisfac- 

 tory reafon is affigned, which determined the 

 water to leave the ore in the vein and no where 



Befides, this hypotheiis does not account 



elfe. 



%r the formation of the fpars and veinllones 

 which fill the vein, and which appear clearly to 

 have been brought there at the fame time with 

 the ore, and no doubt by the fame caufe. 

 233. The veins, properly fo called, are ii 



d 



finitely extended ; but there are alfo thin plates 

 of fpar, and of cryftals of diiTerent kinds, often 

 found included in rocks, and (hut in on all fides. 



to 



h 



\ 



h the 

 Thefe 



lafl 01 

 the fo 



)f \ 

 ght 



plied. 



guifhed fr 



perly be c 



the plate c 



having very often the form of 



5 is commonly ap 

 tainly to be diftin 

 nd may not impro 



d Plate Veins or Lenticular Veins. 



cake of fpar of which they 



flit 



len 



though 



as 



* Geol. EiTays, p. 401. 



