128 PHYSIOGRAPHY. 



Before the blowpipe it melts very easily into a globule, 

 that can be entirely volatilised, during which the support- 

 ing charcoal is covered with a yellow oxide. If dissolved 

 in the state of powder in nitric acid, a precipitate of sul- 

 phur is formed. It consists, according to KLAPEOTH, of 

 Bismuth 95-00. 

 Sulphur 5-00. 



It has been found at Deutsch Pilsen in Hungary, accom- 

 panied by several species of the genera Lime-haloide, Iron- 

 pyrites, &c. 



It seems that in Hungary several species, different from 

 each other, have been designated by the collective unde- 

 termined name of Molybdena-Silver. Thus a species very 

 distinct from that described above, presents the following 

 characters : 



Form probably rhombohedral. It occurs in imbedded 

 masses, having a general resemblance to three and six- 

 sided prisms. 



Cleavage perfect, axotomous. Fracture imperfect conchoi- 

 dal, uneven, scarcely perceptible. 



Lustre metallic. Colour intermediate between tin-white 

 and steel-grey. Streak unchanged, or rather darker, its 

 place becomes shining in the mineral. Opake. 



Very sectile. Thin laminae perfectly flexible. Hardness 

 = 1-5. Sp. Gr. = 7'408. 



This species likewise is found in Hungary. Several 

 specimens of it are in the collection of the Johanneum at 

 Gratz. It is accompanied by hexahedral Gold and pyra- 

 midal Copper-pyrites, imbedded in rhombohedral Quartz. 

 Its chemical compounds are as yet unknown. Before the 

 blowpipe it gives the reactions of sulphur, tellurium, and 

 bismuth. 



Another variety of Molybdena-Silver examined by BER- 

 ZELIUS, which had been communicated to him by Professor 

 WEISS of Berlin, was found to contain only tellurium and 

 bismuth. 



