of the Py jute 6. 29 



gard to copper- ores, I have, from manifold expe- 

 rience and obfervation, made this remark, that fuck 

 fyrita as yield no copper, are always round ; 

 thofe that contain only a little, of eight fides at 

 leaft, and thofe that are richly ftored with copper, 

 commonly exhibiting ten, twelve, and more fides. 



In a word, fo far as my experience in ores and 

 Hones reaches, no one fort exhibits a greater va- 

 riety of figures than the pyrites : and whatever 

 figure nature gives any particular fpecies of bodies, 

 fuch it continues to have unchanged, nature feldom 

 or ever fwerving from the rule fhe has once laid 

 down to herfelf, in any particular fpecies. For 

 inftance, a copper-pyrites is never round, a pure 

 iron-pyrites never angular, leaft of all polygonal ; 

 a glafs-head never like a glitter \ a tin-ftone never 

 regular, &c. The reafons for which muft be ne- 

 cefTary, not accidental, and well defervingour care- 

 ful attention and obfervation 5 for the ftruclure 

 and configuration of minerals may beconfidered as 

 fo many peculiar marks zxA criteria ^ from whence 

 a better judgment may be formed of their na- 

 ture, and confequently a more diftinct defcription 

 and hiflory of them be attainable, at leaft as to 

 their external appearances. 



That divifion and diftinction of pyrita taken 

 From their colour is a capital one ; then I reduce 

 them to three forts, viz. white, yeHowifh, and 

 yellew. 



In confidering the colours of mineral bodies in 

 general, we are to obferve that ores are metal im- 

 pregnated with fulphur, or arfenic 5 orboth : and this 

 is fufficient to conftitute the form or effence of an 



ore., 



fuifleut accuminati ; & latexibus plemmque in illam faciem 

 cxcavatis, ut Jofus fervire potuennt cultris faxeis filiorum 

 Iftad circuir.ciiionem iuipcrami. Aft. tjaftnjsnf T. JY, 

 P- l 17- 



