ON THE RUBIES OF BURMA AND ASSOCIATED MINERALS. 
173 
hidden by the thick covering of hill-wash ; while, in the valley bottoms, they are 
rendered invisible by the deposits of alluvial matters. But in many cases, in these 
positions, their existence is made known through the removal of these superficial 
deposits by the operations of the native miners, in extracting the clays containing 
rubies (see fig. 2). 
Fig. 2. 
Hmyaudwin No. 11. 
Showing pinnacled surface of limestone where hill-wash has been removed. 
It is of the usual composition and character of ordinary crystalline limestones, being 
made up of finely crystalline or granular limestone in layers, together with irregularly 
shaped bands of very coarsely crystalline limestone of white and bluish colours, 
which are interfoliated with the gneissose rocks. The surface of the limestone is 
always serrated and pinnacled by atmospheric action, and contains multitudes of 
sinuous caves leading down in the direction of the bedding planes to greater or lesser 
depths. One of those in mine a is said to have been followed by the miners to a 
depth of 390 feet. In some instances there are also horizontal caves traversed by 
small streams for considerable distances. At mine a, near Kyauksan, which is situated 
in a small depression on the limestone, the water led by a trench down the mountain 
to the mine, for the purpose of disintegrating and washing the ruby clay brought 
out of the tortuous natural pits, is led down an abandoned one in a somewhat turbid 
state, and finds its way to a cave, the mouth of which is at the head of the Kathay 
valley, some distance off. This cave, which I explored for a considerable distance, 
has a good-sized stream flowing in it, which, though rendered turbid by the mine’s 
gutter, contains far more water than is artificially let into it. It has a winding 
course, sometimes along the planes of foliation but also frequently across them, and 
is from 20 to 30 feet in height in places. 
There are eleven distinct limestone exposures between the falls on the Mogok- 
choung and the peak next below Toungnee on the southern slope of that mountain. 
