ORES OF TIN AND TUNGSTEN 79 
comes from scheelite, calcium tungstate (CaWO,). Wol- 
framite is mostly found in quartz-veins in granite; it is of 
Pneumatolytic origin and is associated with quartz, tour- 
maline, topaz, fluorite, and tin. One of the best-known 
fields is Tavoy in South Burma; wolframite occurs there 
in schists which during the uplift of the Altaid Mountains 
at the end of the Palzozoic were intruded by granite and 
Pheumatolytic quartz-veins. According to Morrow Camp- 
bell, tin is present in the lower part and wolframite in the 
upper part of these veins. Wolframite is sometimes mined 
from the lodes, but most of it is obtained by washing gravel 
or decomposed: country rock; these deposits often vield 
3% lb. of wolframite per cubic yard. 
CriNese Deposits—Wolframite occurs under similar 
geological conditions in the province of Kiangsi in Southern 
China. The ore there was at first obtained from alluvial 
deposits, but some quartz-lodes in granite are now being 
mined and also yield some tin. China is now the largest 
producer of tungsten, and in some recent years has supplied 
half the world’s output. Wolframite occurs in Siam, the 
Malay Peninsula, and the Chillagoe and Mt. Carbine fields in 
Queensland. One large deposit of the iron tungstate variety 
of wolframite occurs in Colorado. 
. The chief deposits of scheelite are of Kainozoic age and occur 
nthe western mountains of the United States, especially 
In California ; the scheelite occurs with garnet and epidote 
n limestones altered by granodiorite intrusions. 
Wolframite and scheelite both have nearly the same 
Specific gravity as cassiterite; but wolframite is easily 
Separated magnetically, and scheelite, for which this process 
1S not available, does not often occur with tin oxide. The 
Shot supplies of tungsten come from China, Burma, and the 
od States, the combined yield of Spain and Portugal 
tor 8, fourth in quantity. The output increased from 7800 
io 0 1913 to 21,600 tons in 1017. The material is sold 
ang to the percentage of tungstic acid (WOg); the 
pric: ord quality contains 65 per cent. of that oxide ; the 
dur. as usually varied between 25s. to 35s. per unit, though 
pe the War the output rose to over 30,000 tons in the 
Te and the price to 60s. per unit (or nearly £200 per ton); 
’ 924 the output fell to 5500 tons and the price to as low 
S 0s. 6d. per unit.