ORDER XI. PRISMATIC MELANE-CLAKCE. 



pipe, and is therefore of opinion that it is a compound of 

 sulphur, arsenic, and silver. Before the blowpipe, upon 

 charcoal, it yields a dark coloured metallic globule, which 

 may be reduced either with soda and silica, or with salt- 

 petre. It is soluble in dilute nitric acid. 



2. The prismatic Melane-glance is found in silver veins 

 along with other ores of silver, also with hexahedral Lead- 

 glance, dodecahedral Garnet-blende, and several species of 

 the orders Pyrites, Haloid e, and Baryte. It is sometimes 

 associated with native Arsenic and hexahedral Gold. 

 Prismatic Melane-glance in compact varieties is often inti- 

 mately mixed with hexahedral Lead-glance, and with pris- 

 matoidal Antimony-glance, a mixture designated by the 

 name of White Silver, the Wetssgiltigerz of the \Vernerian 

 system. The richer it is in silver, the more it approaches 

 in its properties to the pure varieties of the present species, 

 while in the contrary cases it yields more nearly the cha- 

 racters of compact hexahedral Lead-glance and compact 

 prismatoidal Antimony. glance, or of a mixture of both, and 

 differs from them perhaps only in the colour. It is evident 

 that the White Silver does not deserve to be ranked as a 

 particular species, on account of this mode of formation, 

 and the variable proportions of the species entering into 

 the mixture. It is found in silver veins in Saxony. 



3. The prismatic Melane-glance occurs chiefly in Saxony, 

 Bohemia, and Hungary ; in the last of which countries it is 

 called R'oschgev'dchs. Its chief localities in Saxony are the 

 mining districts of Freiberg, Schneeberg, and Johanngeor- 

 genstadt, in Bohemia those of Przibram and Katieborzitz, 

 and in Hungary those of Schemnitz and Cremnitz. It is 

 found also at Joachimsthal in Bohemia ; at Andreasberg in 

 the Hartz, here only in small quantities ; at Zacatecas in 

 Mexico, and in Peru. 



4. On account of its considerable contents of silver, it 

 is a valuable ore for the extraction of that metal. 



5. The two following minerals must here be noticed, 

 as they seem to be nearly allied to the prismatic Melane- 

 glance. 



