ECONOMIC GEOLOGY. 



371 



Copper. 



A few small heaps of copper slag were seen lying on the hills 

 _ , . near the Kachin village of Loi Mi, about 



Bawd win. _ , , ,. . .. 



three miles to the west of the -Bawdwin silver 

 mines, and at the head of the valley in which the mines are 

 situated. The ore was probably extracted by the Chinese miners 

 of Bawdwin, but the lode was apparently of no great size or 

 richness ; otherwise the relics of their operations would be more 

 extensive. No traces of the ore in situ could be found. At 

 Bawdwin itself the face of the cliffs is covered in places with 

 films of the brilliant blue and green carbonates of copper, azurite 

 and malachite, which are also found impregnating the country rock, 

 but although it makes a considerable show, the mineral occurs in 

 exceedingly small quantity. It is no doubt to the colours of these 

 carbonates that the place owes its Shan name, Nam-pang-yun, 

 signifying ' stream of the peacock camp.' 



Gem-stones. 



It is not necessary to give here a full description of the gem- 

 bearing gravels of Mogok and Kyatpin in the 

 S kie by ' Sapphire and Rub 7 Mines District, as they have already 

 P Ruby Mines District. been described in detail by Mr. Barrington 

 Brown, and the origin of the gems has been 

 discussed by Prof. Judd in a joint paper contributed to the Philoso- 

 phical Transactions {see ante, p. 34 seq.). The rubies are derived from the 

 crystalline limestone interbedded with the Mogok gneiss ; but attempts 

 to extract them from the rock in situ have proved unsuccessful, 

 and they are obtained from the debris resulting from the weathering 

 of the limestone and associated rocks, either by following up fissures 

 in the former (known as ' loodmn' mining) ; by driving cuttings 

 into the rainwash on the hill sides (Ilwi/uiidian) ; or sinking pits 

 (Twinlone) in the alluvial gravels covering the floor of the valley 

 until the gem-bearing layer [Byon) is reached. The native methods 

 of working are still to be seen in operation in the valley of Kyat- 

 pin (B I), 11 miles to the west of Mogok; but the principal de- 

 posit in the Mogok valley is being worked by the Ruby Mines Co., 

 who have held a virtual monopoly of the industry since the year 

 1889, when they were granted the right to mine for rubies and levy 



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