of the P y r i t e s. 59 



reverts to earth, as iron. Now as iron is the 

 ground and principal, conftituent part of pyrites \ 

 it follows, that the pyrites (together with the un- 

 fulphurated iron-ore, or iron-ftone) is the moft 

 proximate, metallic ore, which in the beginning 

 might have arifen from an unmetallic, unprepared 

 earth. 



True it is, there are earths, which quickly bear 

 metallifation for gold, filver, copper, lead and tin. 

 But in the fir ft place, 'tis here particularly to 

 be heeded, whether for inftance they conftitute, 

 as is pretended the gold and filver clays, or whe- 

 ther they contain only very tender and unobferved 

 eyes or fpangles of thefe metals : again, whether, 

 tho' generally cryed up for their gold and filver, 

 they yield only a very fmall matter thereof; as 

 iron itfelf, efpecially if noble veins join or ac- 

 company its ore ; or if in the iron there be 

 pure native filver interfperfed, it may be faid to 

 contain gold and filver -, but this is not the queftion. 

 Further, it deferves enquiry, whether the gold 

 and filver yields of /inters \ or, thofe marley, ochry, 

 talcky, and calcarious earths, fermenting and ex- 

 uding from fifTures, both in the groove, and often 

 at the day, conftitute their internal, proper mix- 

 tion, or only adhere externally, as in a heap- 

 work \ and thus mixtion and aggregation is here 

 to be well diftinguimed ; feeing, 'tis well 

 known, that ores, nay native grown metals, do, 

 by means of their weathering, lofe their bed, and in 

 length of time, fometimes their ore and metallic 

 form, and revert to an aclual earth - 9 the filver 

 to a white, the gold to a blackifla and grey, 

 which is carried off in a tender earth, in a fluid 

 form, by the waters •, and the former never, the 

 latter often obfervable by the eye ; and in general, 

 on account of their great degree of tenderneis with 

 difficulty, if at all feparable in the buddling or 



warning 



