•256 Of the Principles 



The beds or matrices are, undoubtedly, in fome 

 degree, pre-requifite ; for, though arlmoft each fort 

 of ore be to be met with, confequently generable 

 in various forts of ftone and earth, for inltance py- 

 rites, the univerfality of which is indifputable ; red- 

 goldijh ore, which is to be found on quartz, fpath, 

 ihiver, &c. lead-ore, not only in thefe, but in 

 lime- ftone, and other minerals ; tin-ftone in quartz, 

 fpath, Mufcovy-glafs, and clays ; and we are ftill 

 far from having made fuch difcoveries in the bow- 

 els of the earth, but that many more may remain 

 concealed ; nay, probably, ores may be difcovered 

 in beds where they were never fufpected to lodge, 

 in particular, quartz, horn-fbone, &c. which are 

 the firmeft bodies, prove to be univerfal matrices 

 of ores : yet here it holds not as of the matrices of 

 animals, which are abfolutely neceffary, and con- 

 tribute materially to the birth. 



This is manifefl from experience : however the 

 difference of beds may contribute fomething to the 

 generation of ores-, for, otherwife, why mould 

 lead-glitter be, if not quite a ft ranger,- yet rare and 

 thin fown in Jhiver, whereas pyrites is almoft uni- 

 verfal ; and why fhould tin-ftones never be heard 

 of in fh.iver ? But we are not always to form a 

 judgement of the truth of this proportion from 

 tnixt-work, where ores and minerals are feen mixed 

 together in a furprifmg manner; but then it is in 

 places where two very different veins happen to 

 crofs each other. 



In like manner, fuperfoetations muft not be 

 totally rejected, particularly, where ores and mi- 

 nerals are difpofed in layers, one on the other ; and 

 where, not the undermoft ftone or rock, but each 



layer, 



