ORDER xil. RHOMBOHEDRAL RUBY-BLENDE. 41 



for the dark red, and of 5-4 ... 5-6 for the light red variety. 

 A dark red cleavable variety from the Hartz gave 5-831, a 

 light red one, also cleavable, from Annaberg, 5-524, and a 

 crystallised one from the Churprinz mine near Freiberg, 

 having the colour of the dark red variety, 5-422. This 

 subject deserves the particular attention of mineralogists, 

 though as yet it is impossible to settle any thing in re- 

 gard to the determination of the species. The colours of 

 the Dark Red Silver are dark cochineal-red passing into 

 iron-black, its streak is more or less deep cochineal-red, 

 and it is opake or but faintly translucent on the edges. 

 The colours of Light Red Silver are more distinctly co- 

 chineal-red, but approach in some varieties to those of 

 Dark Red Silver; its streak is light cochineal-red, and 

 often almost aurora-red; it is translucent on the edges, 

 and frequently semi-transparent In these properties, 

 however, the two varieties are joined by transitions. 



2. The rhombohedral Ruby-blende consists, according 

 to BONSDORF, of 



Silver 58-949. 



Antimony 22-846. 



Sulphur 16-609. 



Earthy substances 0-299. 



He gives for its chemical formula 3 Ag S 2 + 2 Sb S 3 , 

 which corresponds to 58-98 of silver, 23-47 antimony, and 

 17*55 of sulphur. It decrepitates before the blowpipe 

 upon charcoal, melts and emits fumes of sulphur and an- 

 timony, after which it yields a globule of silver. It is so- 

 luble in dilute nitric acid. 



3. The rhombohedral Ruby-blende has been hitherto 

 always found in veins, associated with various other ores 

 of silver, with hexahedral Silver, hexahedral Lead-glance, 

 dodecahedral Garnet-blende, and several species of Pyri- 

 tes : the light red varieties often with native Arsenic, pris- 

 matic Iron-pyrites, octahedral Cobalt-pyrites, and other 

 species. 



4. Rhombohedral Ruby-blende is confined to a small 

 number of localities, but in some of these it occurs in pret- 



