ECONOMICS 305 



The exports of domestic zinc ores were 19,953 short tons and 

 the export of zinc dross for the same year amounted to 203 

 short tons. 



The average price of spelter at St. Louis, Missouri, was 6.9 

 cents per pound as compared with 5.7 cents for 1911. 



The United States ranks first as a producer of spelter and is 

 closely followed by Germany and Belgium. The world's 

 production of spelter in 1912 was 956,335 metric tons. 



MOLYBDENUM 



There is annually a small production of molybdenum ore in 

 the United States. The Primes Chemical Company of Primes, 

 Pennsylvania, is the chief manufacturer of molydenum and 

 ferro-molybdenum in this country. 



The price of the metal in 1912 was $1.40 per pound and of 

 the alloy about $1 .60 per pound of its molybdenum content. 



The metallurgical requirement for molybdenite is 92 per 

 cent, molybdenum sulphide. The value of such ore is approxi- 

 mately $400 per ton. To maintain this value the ore must be 

 reasonably free from copper as the latter is an objectionable 

 impurity. 



Lower grade molybdenite ores are valued at about $1 per unit. 

 This holds especially true if the ore concentrates to 25 per cent, 

 molybdenum sulphide. Wulfenite which contains 25 per cent, 

 of molybdic trioxide, MoO 3 , is worth about $100 per ton. 



TUNGSTEN 



According to F. L. Hess of the United States Geological Survey 

 the amount of tungsten ores mined and marketed in the United 

 States in 1912 was 1290 tons carrying 60 per cent, tungsten 

 trioxide, WO 3 . The value of this product was estimated at 

 $492,000. It was a substantial increase over the output of 

 1911. The average price per unit was $6.35. The unit is 1 

 per cent, of a short ton of tungsten trioxide. 



The largest production of any single district came from the 

 unique ferberite deposits of Boulder County, Colorado. About 

 1200 tons of ore was shipped from this district. The Primes 

 Mining and Milling Company and the Wolf Tongue Mining 

 Company are the largest producers. 

 20 



