66 /Scientific Intelligence. 



The mountains are composed of various gneissic and granulitic 

 rocks, occasionally passing into schists. Subordinate to the 

 general mass of gneisses, often containing garnets, are certain 

 peculiar varieties of foliated and massive rocks, including both 

 acid and basic types, with limestone bands, often of a highly 

 crystalline character. It was in these limestones that the rubies 

 and spinels were found to be embedded, associated with graphite, 

 phlogopite, pyrrhotite, and many other minerals. The sides of 

 the hills are found to be shrouded in a deposit of hill-wash, often 

 50 ft. in thickness, composed of fragments, derived from the 

 mountains, embedded in a clayey matrix. On the bottoms of the 

 larger valleys there are extensive level deposits of alluvial matter, 

 consisting of brown, sandy clay, resting on coarse gravels, which 

 in turn cover other argillaceous beds. It is in these lower clay 

 beds of the river alluvia, and in similar deposits formed in gullies 

 in the hill-wash, that the rubies, spinels, and other gems of the 

 district are found. 



Mining operations for the obtaining of rubies are carried on in 

 Burma in four different ways. (1.) In the alluvia, "twinlones," 

 square pits from 2 to 9 ft. across, ingeniously timbered with bam- 

 boo, are sunk to the ruby earth, the drainage of the pits and the 

 removal of material being effected by baskets attached to balance 

 poles, both made of bamboo. (2.) In the hill-wash long open 

 trenches, called " hmyaudwins," are carried from the sides of a 

 gully, and the earth is washed out by streams conveyed into the 

 trenches by bamboo pipes. (3.) In the caves and fissures filled 

 with earth which abound in the limestone rocks, regular mines — 

 "loodwins" — are opened, and the productive ruby earth is fol- 

 lowed for long distances by means of shafts and galleries. (4.) 

 The limestones which contain the rubies are at one or two points 

 quarried, and the gems are obtained by breaking up the rock 

 masses. 



The extensive rubellite mines at Nyoungouk are worked in a 

 somewhat* similar plan to the " hmyaudwins." Water is delivered 

 by a number of bamboo pipes at the head of the almost verti- 

 cally exposed faces of alluvium ; and as the masses of the latter 

 are loosened, the miners dash water upon them from shovel- 

 shaped baskets, and are able to detect and pick out by hand the 

 brilliantly colored stones exposed on the washed surfaces. 



The petrology of this district of Upper Burma, in which the 

 rubies, spinels, and rubellite occur, presents features of the 

 greatest geological interest. In many respects the petrology of 

 Burma exhibits close analogies with that of the corundiferous 

 localities of Ceylon, the Salem district, and other portions of the 

 Indian peninsula ; but some of the phenomena presented by the 

 rocks of the Burma ruby district do not appear to find a parallel 

 in any of the gem-yielding tracts described by de Bournon and 

 more recently by Lacroix. 



The general mass of gneissic rocks composing the mountainous 

 district in which the ruby localities are situated are of interme- 



