PHYSIOGRAPHY. 



Horn Silver. 



3. Horn Silver is most frequently found in the upper parts of veins in 

 clay slate, but occurs also in beds, generally along with other ores of sil- 

 ver ; very often also with ochry varieties of Limonite, or with similar 

 varieties 6f decomposed Iron-Pyrites. It is associated with several spe- 

 cies of copper-ores, and with Calcareous and Heavy Spar. 



4. Formerly, it occurred in considerable quantities in the Saxon mi- 

 ning districts of Johanngeorgenstadt and Freiberg; also at Joachimsthal 

 in Bohemia. In small quantities, it occurs in France, in Spain, atKongs- 

 berg in Norway, in Cornwall, and Silesia ; but in large masses, fre- 

 quently associated with Native Silver, in Mexico and Peru, where the 

 green varieties of colors particularly occur. 



HORNSTONE. (See Quartz.) 



HUMBOLDTINE. 



Msssive : in plates. 



Color bright yellow. 



Soft, yielding to the nail. Sp. gr. = 1-3. 



Acquires resinous electricity by friction. 



1. On ignited charcoal it is decomposed, giving out a vegetable odor, 

 and leaves a metallic stain, at first yellow, then black, and at last red. 

 It is insoluble in water and alcohol. 



2. Analysis. 



By RIVJERO. 



Protoxide of iron - - . . . 53-56 

 Oxalic acid 46 . 14 



3. It occurs imbedded in moor-coal, near Bilin in Bohemia; and is 

 supposed by RIVERO to have been produced from the decomposition of 

 succulent plants. 



HUMBOLDTITE, (See Datholite.) 



HUMITE. 



Primary form. Right rhombic prism. M on M = 120. 



