THE 



GEOLOGLCA.L MAGAZINE 



NEW SERIES. DECADE VI. VOL. V. 



No. v.— MAY, 1918. 



I. — The Genesis of Tungsten Okks. 

 By E. H. Eastall, M.A., F.G.S. 



THE exploitation of tungsten ores on a large scale is of com- 

 paratively recent development. Till lately tlie industrial 

 applications of this metal and its compounds were very limited, and 

 they were regarded rather in the light of chemical and miiieralogical 

 curiosities. In fact, the tungsten minerals were considered a 

 nuisance by miners, owing to the difficulty of separating them from 

 other valuable and equally heavy ores occurring in close association 

 with them. Sodium tungstate was manufactured to a certain 

 extent and used as a mordant in dyeing and for rendering textile 

 fabrics fireproof, and tungstic oxide was sometimes employed in the 

 making of yellow glass. About the year 1905 a demand arose for 

 the metal for electric lamp filaments, but at the present time by far 

 the most important application is in tlie metallurgy of steel. The 

 addition of a small quantity of tungsten, not more than 7 or 8 per 

 cent, together with about 5 per cent of chromium, has a remarkable 

 effect on steel, rendering it both hard and tough and suitable for 

 high-speed cutting tools. Since the beginning of the War the 

 demand for the ores for this purpose has enormously increased, as 

 also has the price; new sources are being sought for and opened up 

 in many localities; in Colorado and California there was a few 

 months ago a tungsten boom recalling the gold rushes of the early 

 days. The resources of various parts of the British Empire are also 

 being exploited on a large scale, and on its nietallurgical side the 

 tungsten industry is now very largely in British hands, whereas 

 before the War Germany absorbed the greater part of the woild's 

 output of ore. Under present conditions it is naturally very 

 difficult to obtain complete and reliable figures, but the following 

 table (p. 194) shows appioximately the output of tungsten ores 

 throughout the world for the last few years. The figures (in tons) 

 are taken from The Mmeral Industry, vol. xxv, p 741, 1916. 



Although the following notes do not claim to contain the results 

 of any original work, it is thought that a brief summary of our 

 present knowledge of the genesis, mode of occurrence, and mineral 

 associations of the tungsten ores may be of interest to geologists and 

 mineralogists. The literature of the subject is widely scattered, 

 largely in foreign publications, and the descriptions in most of the 



DECADE VI. — VOL. V. — NO. V. 13 



