102 COGGIN BROWN : MINES & MINERAL RESOURCES OF YUNNAN. 



The principal deposits are in Triassic limestone the mass of 

 which is impregnated by diffusion from lodes and transformed into 

 a carbonate containing only traces of pyrite. Such deposits take 

 the form of zones of concretions following the natural fissures of 

 the limestone. 



The principal centres of extraction are Tung-ch'uan Fu and 

 Wei-hsi T'ing (tat- 27° 10': long. 99°1 0'). The smelters will only 

 accept minerals capable of producing a matte containing 20 per 

 cent, or 30 per cent, of metallic copper. The ores are hand-picked 

 at the mines to bring this about. Minerals which do not contain 

 more than 15 per cent, metallic copper are thrown away and form 

 considerable dumps. Large quantities of slags containing 3 per 

 cent, copper must exist in the old smelting centres. 



These facts are held to prove that Yunnan possesses consider- 

 able reserves of copper-bearing minerals, chiefly in inaccessible 

 districts. Only general conclusions can be drawn and a special 

 study of each individual deposit is necessary before its value can 

 be determined. (Le. pp. 441-443). 



A great number of copper deposits are capable of a very much 

 larger production, even without great modification of the Chinese 

 mining methods which are quite appropriate for scattered deposits 

 in the Triassic limestone. Leclere thought that a production of 

 10,000 tons per annum was quite possible but that preliminary 

 costs would be high. A special study of the coalfields for suitable 

 fuel to replace wood charcoal is necessary first of all. 



Copper deposits of Eastern Yunnan described by Leclere, Lantenois 



and Deprat. 



I have not visited any of the mines described in this section as 

 they are all situated to the north or south of Yunnan Fu, beyond 

 the limits of my own traverses. 



Deprat believes that the value of the copper deposits of Yunnan 

 has been greatly exaggerated though he admits that there are 

 important mines at considerable distances from the railway (D., 

 p. 247). Most of the numerous deposits between Meng-tzii and 

 Yunnan Fu are not worth the trouble of examination in his opinion. 



Tn 1903 Lantenois concluded that the copper deposits of this 

 region are all more or less in direct association with eruptive rocks 



