356 KEPORT OF NATIONAL MUSEUM, 1899. 



5. SCHEELITE. 



This is calcium tungstate, consisting when pure of some 80.6 per 

 cent tungsten trioxide (WO,) and 19.4 per cent lime; usually, however, 

 carrying from 1 to 8 per cent of molybdic oxide (MoO 3 ). The min- 

 eral is white and translucent, and yellow and brownish in color, with 

 a hardness of 4.5-5, gravity 6, and a tendency to cleave into octa- 

 hedral forms. The occurrence is similar to that of wolframite, but 

 the mineral is less common. 



Uses. The tungstates have been used mainly in the manufacture of 



tungstic acid, but the metal tungsten is coming into use as an alloy 

 in making steel. Recently attempts have been made in France to 

 utilize the material in porcelain glazes, but thus far without much 

 success. There is at present no regular source of supply in America. 



BIBLIOGRAPHY. 



J. PHILLP. Tungsten Bronzes. 



Journal of the Society of Chemical Industry, I, 1882, p. 152. 

 The Use of Wolfram or Tungsten. 



Iron Age, XXXIX, 1887, p. 33. 

 T. A, RICKARD. Tungsten. 



Engineering and Mining Journal, LIII, 1892, p. 448. 

 Wolfram Ore. 



Iron Age, XL, 1892, p. 229. 

 ADOLF GURLT. On a Remarkable Deposit of Wolfram Ore in the United States. 



Transactions of the American Institute Mining Engineers, XXII, 1893, p. 236. 

 See also Engineering and Mining Journal, LVI, 1893, p. 216. 

 F. CREMER. The Place of Tungsten in the Industries. 



Iron Age, LVI, 1895, p. 536. 

 HENRI MOISSAN. Researches on Tungsten. 



Minutes of the Proceedings of the Institution of Civil Engineers, CXXVI, 

 1895-96, p. 481. 

 R. HELMHACKER. Wolfram Ore. 



Engineering and Mining Journal, LXII, 1896, p. 153. 

 Prof. BODENBENDER. Wolfram in the Sierra de Cordoba, Argentine Republic. 



Transactions of the North of England Institute of Mining and Mechanical 

 Engineers, XLV, Pt. 3, March, 1896, p. 59. 



VIII. PHOSPHATES. 

 1. APATITE; ROCK PHOSPHATE; GUANO; ETC. 



Phosphorus is one of the most widespread of the elements, and is 

 apparently indispensable to both animal and vegetable life. In nature 

 it occurs in various compounds, by far the more common being the 

 phosphates of calcium and aluminum, such as are commercially used 

 as fertilizers. These in various conditions of impurity occur under 



