194 EEPORT OF NATIONAL MUSEUM, 1899. 



This mineral, like graphite, occurs, as a rule, in small, black, shining 

 scales, sometimes hexagonal in outline and with a bright metallic 

 luster. It is soft enough to be readily impressed with the thumb nail, 

 and leaves a bluish-gray trace on paper. On porcelain it leaves a lead 

 gray, slightly greenish streak. This faint greenish tinge, together with 

 its property of giving a sulphur reaction when fused with soda, furnish 

 a ready means of distinguishing it from graphite, which it so closely 

 resembles. Through alteration it sometimes passes over into molybdite 

 or molybdic ocher, a straw-yellow to white ocherous mineral of the 

 formula Mo03, = oxygen 33.3 per cent, molybdenum 66.7 per cent. 



Occurrence. — The mineral has a wide distribution, occurring in 

 embedded masses and disseminated scales in granite (Specimen No. 

 62169, U.S.N.M.), gneiss, sj^enite, crystalline schists, quartz (Specimen 

 No. 60995, U.S.N.M.), and granular limestone. It is found in Nor- 

 way, Sweden, Russia, Saxony, Bohemia, Austria, France, Peru, Brazil, 

 England, and Scotland, throughout the Appalachian region in the 

 United States and Canada (Specimen No. 53(M6, U.S.N.M.), and in 

 various parts of the Rocky and Sierra Nevada mountains. In Okan- 

 ogan County, Washington, the mineral occurs in beautiful large flakes 

 in an auriferous quartz vein traversing slates. (Specimen No. 53126, 

 U.S.N.M.) 



On Quetachoo-Manicouagan Bay, on the north side of the Gulf of 

 St. Lawrence, the mineral is reported ^ as occurring disseminated in a 

 bed of quartz 6 inches thick, in the form of nodules from 1 to 3 

 inches in diameter and in flakes which are sometimes 12 inches broad 

 by i inch in thickness. 



Molybdenite is also found in the form of finely disseminated scales 

 or small bunches among the iron ores of the Hude mine at Stanhope, 

 New Jersey, sometimes constituting as high as 2 per cent of the ore. 



Molybdenum is also a constituent of the mineral wulfenite, or 

 molybdate of lead. 



Uses. — The principal use to which molybdenite has as yet been put 

 is in the preparation of molybdates for the chemical laboratory. It 

 is stated that a fine blue pigment can be prepared from it, which 

 it has been proposed to use as a substitute for indigo in dyeing silk, 

 cotton, and linen. The metal molybdenum is produced but rarely and 

 only as a curiosity, and has a purely fictitious value. Up to the present 

 time there has been no constant demand for the mineral nor regular 

 source of supply. 



^ Geology of Canada, 1863, p. 754. 



