204 
MR. C. BARRINGTON BROWN AND PROFESSOR J. W. JUDD 
occurs in fragments in the ruby gravels, but this rock contains hypersthene as well 
as augite. 
Pyroxene-gra.nulites, with both augite and enstatite (hypersthene) and the plagio- 
clase felspar more or less completely altered to scapolite, occur, by no means rarely, 
in the ruby gravels, as at the Hmyaudwins Nos. 9 (see Plate 6, fig. 6) and 13 at 
Mogok. In many cases, however, the pyroxenes are more or less completely altered 
into hornblende and biotite. In one case I have found the augite changed to the 
schillerized forms—diallage and pseudo-hypersthene. 
While some of the pyroxene-gneisses are rich in felspar arid contain some ortho- 
clase, others are remarkable for the abundance of the ferro-magnesian silicates, and 
when all the alumino-alkaline silicates disappear, these rocks pass into the pvroxenites, 
or by alteration into amphibolites. These rocks consist of an augite, sometimes nearly 
colourless, at other times green, and occasionally purplish in tint, and more or less 
hornblende, evidently formed by the alteration of the pyroxene. Enstatite (hyper¬ 
sthene or bronzite) is also sometimes present. The colourless minerals—plagioclase 
in various stages of Werneritization—and quartz and calcite are so rare that they can 
only be regarded as accessory. In addition we find spliene, both original and second¬ 
ary (titanomorphite), apatite and titanoferrite. 
At the mine No. 14 at Mogok there occurred a rock of this kind, consisting of nearly 
equal parts of a purplish-brown augite and a deep-brown hornblende, very similar 
to basaltine (basaltic hornblende). There are clear indications that the hornblende is 
paramorphic after the augite. In this case only minute and inconsiderable quantities 
of the white minerals (felspar, quartz, calcite, and scapolite) are present. 
in a Loodwin, near the Momeit-Boad Pass, a rock consisting of a dark-green augite, 
occasionally changed to a brown hornblende, is found. The rock also contains some 
wollastonite, and is interesting, as it is seen to be interfoliated with a crystalline 
limestone, the one rock passing insensibly into the other. 
At the pass from Kyatpyen into the next valley to the west, there is a rock which 
seems to have originally consisted of a colourless augite with some brown sphene. 
The greater part of the augite has now been converted into a brown hornblende, and 
the pyroxenite has been converted into an amphibolite. 
The connection between these rocks, so rich in ferro-magnesian silicates (“ ultrabasic 
gneisses : ’) and the calcareous rocks is often of the most intimate kind. 
The last of these basic rocks which we have to notice are those which contain the 
beautiful blue minerals—coloured by a sulphur compound—hauyn and lazurite (lasurit 
of Brogger). The blue crystals a,re isotropic, and vary greatly in the intensity of 
their tints, consisting in all probability of hatiyne, and perhaps sodalite, as well as 
lazurite. The blue mineral is accompanied by a colourless pyroxene (diopside), with 
calcite, scapolite, epidote, and other colourless minerals, the whole forming a very 
beautiful lapis-lazuli rock. (See Plate 6, fig. 9.) 
There are two varieties of this rock. In one the blue isotropic minerals do not 
