ON THE RUBTES OF BURMA ANT) ASSOCIATED MINERALS. 
163 
20 yards wide, and 10 feet deep, the brown loamy gem-bearing clay encloses large 
round blocks of decomposed pegmatite, which are reduced to the consistency and 
appearance of flour, with also some rusty black decomposed crystals. Some pits 
have been sunk in the floor of the mine to a depth of 18 feet, without reaching 
bed rock. The upper portion of one pit discloses layers of stream sand and pebbles, 
some 10 feet in thickness, mixed with brown loam. Beneath this is brown clay, in 
which are embedded large boulders of gneiss and pegmatite. 
At No. 22 mine, near Sinkwa (Shinkwa) village, the section disclosed is some 
150 feet wide, with a depth of 20 feet. The nature of the deposit shows a more 
bedded character than usual. The face of the mine on the west exposes 10 feet of 
brown clay, of which the upper portion is unproductive. 
The clay in another part contains much water-worn pebbles, with blocks of gneiss 
and quartz which are not rounded. There is a band of blue clay lying horizontally 
in it, and at the base of the section are angular blocks of grey gneiss. 
From a study of these sections it would appear that the brownish loamy clay, con¬ 
taining gems, has been made up of materials derived from the decomposition of 
gneissic rocks, mixed with a preponderating proportion of clayey matter and 
minerals derived from the disintegration of the crystalline limestone. 
Amongst the ruby clays of this deposit are numerous pebbles of quartz and other 
rocks, which are completely waterworn, but the majority are not so, whilst in some 
instances scarcely any of them show any signs of attrition. For instance, the 
numerous bluish, opaque spinels are in their crystalline form of twin octahedrons, 
whilst perfect crystals of quartz are not uncommon, occurring with a small amount 
of water-worn pebbles of the same mineral. Also the rubies and red corundum, 
though sometimes found in a waterworn condition along with these, have usually, 
though broken, scarcely suffered from abrasion in any way. From these facts I 
conclude that none of the minerals in the ruby clays of this deposit have been 
transported to any great distance from the source of their origin, and that the 
rounding of some is rather to be attributed to attrition in pot holes, on rock surfaces, 
in the beds of small mountain streams. The fact of the minerals being intimately 
mixed with the brown clays, shows also that the whole deposit has been moved down 
the mountain sides without being submitted to forces sufficient to produce a thorough 
re-sorting of the component materials. 
On washing the ruby-bearing materials of this deposit, and eliminating the clay 
and fine sand, the remaining portion is found to be made up of quartz, gneiss, 
pegmatite, black tourmaline, garnet, rock crystal, spinel, and ruby. In some 
Hmyaudwins, notably No. 1 and No. 2, a few sapphires have been found, but 
very sparingly. In some of these mines it is said that the upper red loamy clay 
contains rubies in infinitesimal quantity. In No. 2 mine large pieces of pale red, 
opaque corundum are found, some of which, though broken, retain a part of their 
crystalline form. 
y 2 
