ORDER ix. NATIVE ARSENIC. 423 



ORDER IX. METAL. 



GENUS I. ARSENIC. 

 1. NATIVE ARSENIC. 



Native Arsenic. JAM. Syst. Vol. III. p. 104. Man. p. 

 257. Native Arsenic. PHILL. p. 275. Gediegen Ar- 

 senik. WERJT. Hoffm. H. B. IV. 1. S. 207. Gediegen 

 Arsenik. HAUSM. I. S. 120. Gediegen- Arsenik. LEOXH . 

 S. 164. Arsenic natif. HAUY. Trait^, T. IV. p. 220. 

 TabL comp. p. 108. Trait**, 2de Ed. T. IV. p. 236. 



Regular forms and cleavage unknown. 



Lustre metallic. Colour tin- white, a little inclining 

 to lead-grey, very soon tarnished dark-grey on 

 being exposed to the air. Streak unchanged, ra- 

 ther shining. 



Brittle. Hardness = 3-5. Sp. Gr. = 5.766, a 

 Saxon variety. According to BERGMANN, that 

 of the melted arsenic is = 8-308. 



Compound Varieties. Reticulated, reniform and 

 stalactitic shapes : composition granular, small and 

 often impalpable ; it is sometimes columnar, form- 

 ing a second curved lamellar composition ; the indi- 

 viduals being generally impalpable, and the faces of 

 the second composition reniform or uneven. In co- 

 lumnar particles of composition we may often observe 

 cleavage in a direction perpendicular to the axis of the 

 individuals. Massive, sometimes with impressions. 



OBSERVATIONS. 



1. Native Arsenic is the pure metal as produced by na- 

 ture. Two varieties yielded to JOHN, 



Arsenic 96-00 97'00. 



