366 RESEARCH IN CHINA. 
pages. Good exposures are to be seen along the stairway up the T’ai- 
shan at altitudes between 4,000 and 5,000 feet, 1,200 and 1,500 meters, 
above sea-level. Specimen 30 was taken there at 4,200 feet, 1,260 meters, 
elevation. 
A medium-grained black-and-white gneiss with wavy banding. White 
lenticular spots or ‘“‘augen’”’ are developed on a small scale, but the feature 
is hardly prominent enough to justify the application of the term ‘‘augen- 
gneiss’ to the rock. The foliation planes are dark with leaves of brown 
and black mica, together with a subordinate amount of hornblende. The 
quartzes and feldspars are for the most part glassy or white in color, 
occasionally with flesh-colored tints. 
The preponderant minerals in this gneiss are quartz, plagioclase, 
orthoclase, microcline, and biotite; with hornblende, epidote, titanite, mag- 
netite, and apatite as accessories. 
The quartzes all show effects of mechanical strain. In most of the 
crystals strain-shadows are prominent, and many contain streaks of inclu- 
sions. Some of them have been fractured and exhibit incipient granulation 
at some of the points of contact with other crystals. 
Among the feldspars a sodic plagioclase which occurs in large crystals, 
particularly in the lenticular ‘‘augen,’’ seems to be an original constituent 
of the rock. In contrast to the fresh crystals of the potassic varieties 
associated with it, this feldspar is almost always considerably altered 
to saussurite and mica. ‘The orthoclase also seems to be, for the most 
part, an original mineral, but certain clear grains are almost surely of a 
secondary nature. It is frequently cracked and may show granulation 
at some points, as does the quartz. The microcline is apparently confined 
to the areas of quartz-and-feldspar mosaic which are obviously the result 
of recrystallization; the feldspar, in these cases, occurs in small crystals 
which are perfectly fresh. 
The dark bands in the gneiss are composed, for the most part, of inter- 
laced leaves of biotite, and green hornblende. ‘Their freshness, their parallel 
arrangement, and their segregation apart from the lighter zones of quartz 
and feldspar, indicate that both of these darker minerals have been 
developed during the process of metamorphism. ‘The biotite is dull brown 
in color and is almost unaltered. The hornblendes are deep green, pleo- 
chroic, and frequently occur in twinned crystals. A certain amount of 
mechanical deformation seems to have taken place since the hornblende 
was formed, for some of the crystals have been bent or fractured. 
Alterations of the hornblende to biotite and grains of epidote are not 
infrequent—a process which is known to be characteristic of the zone of 
