PHYSIOGRAPHY* 67 



Black Silver. 



Surface of the prisms striated vertically. 



Lustre metallic. Color iron-black. Streak unchanged. 



Sectile. Hardness =2-0 . . . 2*5. Sp. gr. = 6-269 from 

 Przibram ; =5-5, from Freiberg. 



Compound Varieties. Twin-crystals like those of Ar- 

 ragonite. (q. v.) Massive : composition granular, individ- 

 uals strongly connected ; fracture uneven. 



1. Before the blow-pipe, upon charcoal, it yields a dark colored metal- 

 lic globule, which may be reduced either with soda and silver, or with 

 nitre. It is soluble in dilute nitric acid. 



2. Analysis. 



By KLAPROTH. By BRANDES, 



from Freiberg. 



Silver - - - 66-50 - - - 65-50 

 Antimony - - 10-00 ... 0-00 



Arsenic - - 0-00 - -. - 3-30 



Iron 5-00 - - - 5-46 



Sulphur - - 12-00 - - - 19-40 



Copper and arsenic - 0-50 ... 0-00 



Copper - - 0-00 - - - 3-75 



3. Black Silver occurs in silver-veins along with other ores of silver, 

 also with Galena, Blende, Copper and Iron Pyrites, Heavy Spar, &c. It 

 is sometimes associated with Native Arsenic and Native Gold. Its com- 

 pact varieties are often intimately mixed with Galena and with Stibine, 

 a mixture designated by the name of White Silver, the Weiss geltigerz 

 of WERNER. The richer it is in silver, the more it approaches in its 

 properties to the pure varieties of Black Silver ; while in the contrary ca- 

 ses, it presents more nearlylhe characters of compact Galena and of com- 

 pact Stibine, or of a mixture of both. It occurs in the silver veins of 

 Saxony. 



4. Black Silver is found chiefly in Saxony, Bohemia and Hungary ; in 

 the last of which countries it is called Roschgewachs. Its chief locali- 

 ties in Saxony are the mining districts of Freiberg, Schneeberg, and 

 Johanngeorgenstadt ; in Bohemia, those of Przibram and Ratieborzitz ; 

 and in Hungary those of Schemnitz and Cremnitz. It is found also in 

 small quantities in Andreasberg in the Hartz ; and at Zacatecas in Mex- 

 ico, and in Peru, as well as in Siberia. 



