of the Pyrites. 25 



of loofe teeth, accurately fitting the fides, as if 

 let with the greateft care. 



The round pyrites, as was before obferved, is ei- 

 ther fpherical or hemi-fpherical The fpherical, or 

 whole round, have in the middle a point, from which 

 fhoot radii to the circumference, where thefe radii 

 always project, either in lmooth bodies, or in (harp 

 points, often undiftinguifhable ; and again, often 

 flriking the eye. The hemi-fpherical, which are thofe 

 arched, or bulging on one fide only, are partly ra- 

 diated, partly coated ^both commonly confiding of 

 an impure, namely, an arfenical fulphur, and being 

 alfo fomewhat coppery ; whereas the whole-round 

 are generally without either arfenic or copper, and 

 therefore yield the pureft fulphur and iron-vitriol. 

 Befides thefe there is alfo a broadifh, oval, round 

 fort, ufually called pyrites-kidnies ; alfo a botrytes, or 

 cluftered fort, confuting, as it were, of pure, fmall 

 globules (whither alfo are referable the criftated fort) 

 and fuch configurations we often meet with in the 

 blood ] ft one, or glafs-head : the cylindrical fort are 

 caft in the fhell of that fea-fifh, from which the 

 belemnites takes its figure, The cone-round, the 

 cochlites, &c. have fome fea-fhells, in which nature 

 has lodged and formed them, for the ground of 

 their figure. 



Scheuchzer has obferved many of thefe round 

 pyrites in Switzerland, wafhed down by rains and 

 water-floods from the heights of the Alps, and 

 fuppofed to be lapides fulminares, thunder-ftones ; 

 not fmooth, but unequal and rough ; of a rufly 

 caft, appearing radiated upon breaking, and glit- 

 tering of the colour of gold and filver*. But he 

 fhould have told us whether it was on account of 

 their contents, or their colour, that he calls them 

 coppery {pyritas areos) as I have not hitherto ob- 



fervftj 



* Iter, Alpin, I, p, 2. 



