202 
MR. C. BARRINGTON BROWN AND PROFESSOR J. W. JUDD 
scapolite, which has cleai’ly been derived from a plagioclase felspar, quartz, some of 
which is quite free from bands of inclusions and is probably secondary, and calcite, 
grains of which are by no means rare ; the accessory minerals are garnet, sphene, 
and zircon. 
On the road from Mogok to Momeit a rock occurs in situ which contains a white 
augite (sahlite or malacolite), a ferriferous enstatite (hyperstnene), and a little biotite 
with some magnetite or titanoferrite in large grains (see Plate 6, fig. 4). The white 
augite is similar to that found at Toungnee, and the hypersthene shows the usual 
pleochroism of an enstatite moderately ferriferous. The remainder jof the rock is 
almost wholly made up of grains of scapolite, some of which show, however, in the 
Fig. 15. 
Pyroxene-gneiss, from Mogok. x 3 diameters. The dark crystals are a pale-green augite. The 
paler crystals a yellowish-brown sphene, and the rest of the slide is made up of a basic felspar near 
anorthite, which, in this instance, has undergone but little change. 
presence of faint traces of lamellar structure that they have been produced by the 
alteration of a plagioclase. The brown biotite of this rock appears to have been 
formed by the alteration of the sahlite. 
A variety of the sahlite-cranulite rock from Tounnnee hill is interesting as exhibit- 
ing the alteration of the white augite into brown biotite and the plagioclase felspar 
into scapolite. Every stage of these interesting changes may be traced in this parti¬ 
cular rock, which also contains a considerable quantity of hypersthene. 
Near the cantonments at Bernardmyo there occurs a coarser grained variety of 
these rocks, distinguished by the limited amount of ferro-magnesian silicates and the 
presence of orthoclase. The augite of this rock is largely altered to hornblende and 
biotite. In No. 18 Hmyaudwin at Mogok a very similar rock (see Plate 6, fig. 1.) 
