REPORT ON MINERAL VEINS. 13 



geologists of the present day, the veins of granite, porphyry, 

 quartz, &c. 



Some of these have been examined below the surface, where 

 they pass through coal-fields, or other deposits of useful mine- 

 rals, but containing in themselves nothing to reward the toil of 

 exploring them : little has been seen of their contents and con- 

 figuration, and our knowledge of them is more limited. 



Lastly, there are tortuous and irregular veins or ramifications 

 in most rocks, extending to limited distances, as far as our ob- 

 servations permit us to judge, seldom oflfering a valuable return 

 for any effort to explore them, and of which, therefore, our 

 knowledge is but superficial. 



Such veins, according to Mr. Came, have been usually di- 

 stinguished from true veins by their shortness, crookedness, 

 and irregularity of size, as well as by the similarity of the con- 

 stituent parts of the substances which they contain to those of 

 the adjoining rocks, with which they are generally so closely 

 connected as to appear a part of the same mass. Two other 

 distinctive marks may be added ; one is, that when they cross; 

 they do not exhibit the heaves of true veins, but usually unite ; 

 the other is, that when there is an apparent heave it is easy to 

 perceive that what appear to be separate parts of the same vein 

 are different veins terminating at the cross vein. 



Such may be, probably, of contemporaneous formation ; and 

 there may be deposits of ore also which it would be difficult to 

 refer the structure of to any other hypothesis, particularly such 

 as contain ores so intimately mixed with the rocks as to form a 

 constituent pai't of them. 



I would suggest, that if from any one of these classes we were 

 to form a judgement as to the whole, error would probably be 

 the consequence, or, at any rate, the view would be a narrow 

 and contracted one, and our decisions would be defective in 

 many important respects. 



To have conducted the inquiry in this manner seems to me 

 to have been the error in many who have preceded us in for- 

 warding the state of knowledge on vein formations. Nor do I 

 mean to detract from the great merit of many of them on this 

 account ; the field of observation is too vast to become fully 

 acquainted with it ; it extends over the most rugged parts of 

 the earth's surface, and its boundaries are not reached in the 

 deep recesses of its bowels. It is no wonder that in the earlier 

 stages of such inquiries men should be strongly impressed with 

 what lay immediately before them, and should view with dis- 

 trust what they might only learn from description. 



Such impressions may be traced in looking at the authors of 



