2 4 2 A SYSTEM OF 



APPENDIX. 



SECT. CCLIX. 



IHave already in the Preface mentioned the rea- 

 fons why the Saxa and Foilils commonly called 

 Petrefactions, cannot be ranked in a mineral 

 fyftem : And I am almoft perfuadcd, that the fame 

 reafon which has prevailed on me, will likewife 

 after mature confideration be approved by others. 

 Mean while, iince thefe bodies, efpecially the lat- 

 ter, occupy fo confiderable a place in moil mine- 

 ral collections x and the former mult neceflaiily be 

 taken notice of by the miners in the obfervations 

 they make in the fubterranean geography, I 

 would not entirely omit them here, but have 

 tried to put them in fuch an order as may anfwer 

 that purpofe, for which miners and mineralifts pay 

 any regard to them. 



SECT. CCLX. 



The FIRST O R D E R. 



SAXA.. P E T R JE, 



T divide thefe into two kinds. 

 i. Compound Saxa, Saxa compqfita r 



Are fuch fcones whofe particles, confiding 

 of different fubflances, are fo exactly fitted 

 and joined together, that no empty fpace, or 

 even cement, can be perceived between them ; 

 which feems to indicate, that fome> if not all, 



ol 



