MINERAL RESOURCES OF THE STATE OF NEW YORK 163 



MOLYBDENITE 



This mineral has not been mined in New York but it occurs in 

 a number of locaHties and possibly may be present somewhere in 

 economic quantity. It is the principal ore of the rare metal molyb- 

 denum, for which a demand has developed of late in connection with 

 the manufacture of alloy steels for special uses. One of the applica- 

 tions of molybdenum steel is in the lining of heavy ordnance; it is 

 said to be more resistant to erosion from the gases of high explosives 

 than other kinds of steel, and guns so lined consequently give pro- 

 longed service. Molybdenite is a sulphide (MoS) and bears a 

 striking resemblance in physical characters to graphite. It is soft, 

 of lead gray color and occurs in small scales and thicker plates, 

 rarely showing hexagonal outlines. Its streak on glazed porcelain 

 has a greenish tint quite distinct from the grayish black graphite, 

 the best physical test for its recognition. 



Molybdenite has a fluctuating market, but ordinarily is in request 

 at prices which make a deposit of economic interest that carries 

 only I or 2 per cent of the mineral. A deposit of this kind should 

 be large and the ore amenable to concentration without excessive 

 loss of the valuable mineral. Owing to its softness, molybdenite 

 crushes readily into powder and then is separated with difficulty. 

 Flotation has been applied successfully to ores containing dissem- 

 inated molybdenite, such as are mainly represented in this State. 



The mineral is foiind in various associations, but more especially 

 with granitic rocks and their offshoots and along contacts between 

 granite and limestone. Several localities for its occurrence have 

 been listed by Whitlock^, as follows: Manhattan Island, between 

 43d and 44th streets and First and Third avenues, in mica schist; 

 West Point, Orange county, in gneiss; Constitution island (Hudson 

 river off West Point) in gneiss; Warwick, Orange county, in lime- 

 stone; TiUy Foster mine, near Brewster, Putnam county, in serpen- 

 tine; North Russell, St Lawrence county, gneiss-limestone contact. 

 Of these localities the one in New York City is no longer accessible. 

 From what has been learned indirectly it is evident that the West 

 Point, Constitution island and Warwick occurrences have little or 

 no interest except from a collector's standpoint. At the Tilly Foster 

 mine molybdenite occurs sparingly as a contact mineral in meta- 

 morphosed limestone and is no longer to be found except in the waste 

 dumps of the former workings. 



The Russell locaHty, about which little was previously known, was 

 visited in 1917 by A. F. Buddington, who commimicated to the 



1 New York Mineral Localities. N. Y. State Mus. Bui. 70, 1903. 

 6 



