438 



DESCRIPTIVE MINERALOGY. 



ORDER VIII. MOLYBDENUM. 



This includes only a single species, viz : 



1. Molybdenite. 



Fig. 531. 



MOLYBDENITE. 



[From the Greek (aoXuS^os, lead ; because of its resemblance to that metal.] 



Molydcne Sulfure. Havy. — Sulphuret of Molybdena. CUaeeland and Phillips. — Molybdenite. S/tepard. — 

 Bisulphide of Molybdenum. TTumson. — Rhombobedral Molybdena. Jameson. — Dirhomboedrischer Eutom- 

 Glanz. Mohs. — Molybdenite. Beudant. 



Description. Colour pure lead-grey. It occurs crystallized in very flat six-sided prisms, 

 which are easily divisible parallel with their terminal planes ; also massive, with a lamellar 

 structure. Primary form the regular six-sided prism. Fig. 531. 

 Cleavage perfect parallel with P. Lustre metallic. Opaque. Sectile, 

 approaching to malleable. Thin plates are highly flexible, but not 

 elastic ; unctuous to the touch. On porcejain or pottery, it leaves 

 a greenish streak ; on paper, traces of a metallic grey colour. Hard- 

 ness from 1 .0 to 1.5. Specific gravity from 4.40 to 4.70. Before 

 the blowpipe, it gives out sulphureous fumes, which are deposited on the charcoal ; but it 

 is infusible, and is not reduced. It is soluble with eflervescence in nitric acid, leaving a grey 

 residue, which becomes blue when it is brought in a moist state in contact with a plate of zinc. 

 Heated with nitre in a platinum spoon, it deflagrates strongly with flame. 



It may be distinguished from graphite which it often closely resembles, by the above cha- 

 racters, but especially the difference of its streak on porcelain. 



Composition. Molybdenum 60 . 00, sulphur 40.00 (jBmcAoZz). Formula MoSj. 



Geological Situation. This mineral occurs imbedded in granite, gneiss and other pri- 

 mary rocks. It is often associated with quartz. 



Uses. It is from this ore that the metal and its compounds are usually prepared. 



LOCALITIES. 



Molybdenite has not heretofore been found very abundantly in this State. It has, however, 

 been met with in Clinton county ; on the island of New- York ; and in various parts of the 

 Highlands, as at West-Point, at the Phillips iron mines, etc. It has also been found in irregu- 

 lar plates, associated with iron pyrites, rutile, zircon, etc., in granite, two miles southeast of 

 the village of Warwick in Orange county. 



