ORDER n. PRISMATIC ANTIMONY-BAEYTE. 153 



dered as simple forms, and the faces of composition 

 as faces of cleavage with a pearly lustre. In trying 

 the experiment of ascertaining their hardness, we 

 must be careful, on account of the crystals being 

 very fragile. Massive : composition granular, la- 

 mellar, columnar ; faces of composition of the gra- 

 nular individuals in general irregularly streaked. 



OBSERVATIONS. 



1. The present species I formerly included in the order 

 Mica, as prismatic Antimony-mica. Owing to the com- 

 pound state of the then known varieties, among others those 

 from Przibram, and which was considered as cleavage, the 

 true cleavage has long been overlooked, and the hardness 

 examined in the same varieties indicated as less consider- 

 able than it is in nature. Simple varieties of the species 

 have since been found at Braunsdorf near Freiberg, which 

 yielded the characters indicated above, and which have even 

 served to simplify the Characteristic. 



2. According to VAUQUELIN, the present species con- 

 sists of 



Oxide of Antimony 86-00. 



Oxide of Antimony and Iron 3-00. 



Silica 8-00. 



It is pure oxide of antimony, s'b, according to BERZELIUS, 

 equal to 84-32 of metal, and 15-68 of oxygen. It is 

 soluble in nitro-muriatic acid. It melts at the flame of a 

 candle. Before the blowpipe, upon charcoal, it is en- 

 tirely volatilised, and produces a white coating upon the 

 support. It is frequently produced during chemical ope- 

 rations, and crystallised from sublimation. If metallic an- 

 timony is melted before the blowpipe, it emits fumes which 

 crystallise round the globule, and at last cover it entirely. 

 First yellowish octahedral crystals, probably of antimo- 

 nious acid, are formed, and then a beautiful tissue of acicu- 

 lar prisms of oxide of antimony. They are sufficiently 



