18 PHYSIOGRAPHY. CLASS II. 



GENUS V. MOLYBDENA-GLANCE. 

 1. RHOMBOHEDRAL MOLYBDENA-GLANCE. 



Rhomboidal Moljbdena. JAM. Svst. VoL III. p. 372. 

 Man. p. 282. Sulphuret of Molybdena. PHILL. p. 

 248. Wasserblei. WERN. Hoifm. H. B. IV. 1. S. 

 231. Wasserblei. HAUSM. I. S. 197. Molybdanglanz. 

 LEONH. S. 162. Molybdene sulfure'. HAUY. Traite', 

 T. IV. p. 289. Tabl. comp. p. 114. Traite', 2de Ed. 

 T. IV. p. 326. 



Fundamental form. Rhombohedron, of unknown 

 dimensions. Vol. I. Fig. 7. 



Simple forms. R x ; P ; P -f oo. They oc- 

 cur in combination with each other, and seem to 

 possess a di-rhombohedral character. 



Cleavage, R QD, highly perfect. Fracture not 

 observable. Surface, R oo smooth ; P and 

 ' P + oo horizontally streaked. 



Lustre metallic. Colour pure lead-grey. Streak 

 unchanged. 



Thin laminae are highly flexible. Very sectile. 

 Hardness = 1-0 ... 1-5. Sp. Gr. = 4-591. 



Compound Varieties. Massive : composition 

 granular, of various sizes of individuals. 



OBSERVATIONS. 



1. According to BUCHOLZ, rhombohedral Molybdena- 

 glance consists of 



Molybdena 60-00. 



Sulphur 40-00. 



It does not melt, nor is it reduced before the blowpipe, but 

 it emits sulphureous fumes, which are deposited on the 

 charcoal. It deflagrates with nitre, and is soluble with 

 effervescence in nitric acid, leaving a grey residue. 



