ON THE RUBIES OF BURMA AND ASSOCIATED MINERALS. 
227 
enstatite; the former showing the two sets of secondary parting planes, 
characteristic of “ pseudo-hypersthene,” the latter being highly ferriferous 
and strongly pleochroic (hypersthene). The rock was obtained from 
Hmyaudwin, No. 13, Mogok. X 1 3 -. 
Fig. 2. Pyroxene-granulite, with scapolite and calcite. This rock consists largely of 
an untwinned felspar in rounded grains, among which are many grains of 
scapolite and a considerable number of grains of calcite. The rock is very 
distinctly foliated, and streams of liquid cavities can be traced passing con¬ 
tinuously through contiguous grains. The ferro-magnesian silicate is a 
purplish, non-pleochroic augite, probably titaniferous. The rock was 
obtained, in situ, at Letnytoung mountain. X - 3 -. 
Fig. 3. Sahlite-scapolite granulite. In this rock the whole of the felspar appears to 
be converted into scapolite, with some calcite. The pyroxene is a white 
augite (sahlite) which, on the outer margin of its granules, sometimes 
shows tendency towards an alteration to a brown pleochroic material 
(biotite). Granules of sphene are by no means rare. The rock was 
collected, in situ, at Toungnee mountain. X - 3 ~. 
Fig. 4. Sahlite-hypersthene-biotite-granulite. This rock contains not only a mono¬ 
clinic pyroxene, like the last, but also a considerable amount of a highly 
coloured and pleochroic rhombic pyroxene (hypersthene), as well as a 
number of grains of biotite and magnetite, or titanoferrite. There is 
much quartz, a little plagioclase felspar, and possible orthoclase also. 
The rock was collected, in situ, on the road leading across the pass 
between Mogok and Momeit. X 
Fig. 5. Pyroxene-biotite-hornblende-hypersthene-granulite with scapolite. This rock 
differs from the last in having a brown hornblende in addition to the 
colourless pyroxene, in the relative abundance of the several constituents, 
and in the large amount of plagioclastic felspar in places largely converted 
into scapolite. The quartz is present in much smaller quantities A 
part, at least, of the colourless pyroxenic constituent appears to be 
wollastonite. This rock was collected in a Loodwin, Kathay. 
Fig. 6. Hornblende-sahlite-granulite. The pyroxene in this rock sometimes shows 
the first trace of a paramorphic change into hornblende by very faint 
pleochroism. The plagioclase felspar is almost entirely unaltered, and 
there is little or no quartz or calcite in the rock. The rock was collected 
in No. 9, Hmyaudwin, Mogok. X - 3 -. (N.B.-—The part of the slide 
figured shows but little sahlite, this mineral being somewhat locally 
distributed.) 
Fig. 7. Pyroxenite associated with the limestones of Burma. This rock consists 
almost wholly of a green pyroxene with a little quartz and plagioclase 
felspar and some sphene. In other cases, however, the pyroxene is 
2 g 2 
