67 



We have here figured what appears to be one of the 

 largest crystals that have yet been seen: it is terminated at 

 both ends with short columns in the form of plates, and 

 stuck sideways on the gangue ; the column forming hexae- 

 dral faces, chiefly on account of the deepness of the other 

 faces, and the decrease towards the middle, mentioned at 

 tab, 135. Thus the face decreasing on the column is re- 

 duced to a small triangle : see right hand figure. On this 

 crystal we also observe another modification that has not 

 yet been mentioned by Count de Bournon, viz. the upper 

 face on the corner of what he calls the primitive prism, 

 forming from the terminal face probably at the same angle 

 with those on a line with the prism : see figure a. 



Mr. Hatchett, after a careful analysis, found it to 

 contain : 



Lead . . 



. 42-62 



Antimony 



. 24*23 



Sulphur 



. 17 



Copper 



. 12-80 



Iron . . 



1*20 



Loss . . 



2*15 





100' 00 



It is of a grayer colour, and much more fusible than 

 Galena, as it melts before it is red hot ; it leaves a cupreous 

 residuum, whereas the fibrous part — tab. 135 — leaves scarce 

 any. Its lustre is very great. Fig. 1 points out the faces 

 of the column, which are very small. The right hand figure 

 is the natural crystal ; and the left hand figure is a geome- 

 trical outline, to explain the faces above and below the 

 column. 



