456 RESEARCH IN CHINA. 
Buff micaceous marble, No. 117.—This buff marble occurs in layers 
2 to 4 feet in thickness, embedded in biotite schists (No. 115) from Liang-ho 
to Ta-ho-pa. ‘The series is evidently equivalent to a portion of the Paleo- 
zoic rocks exposed in the canyon of the Han river, and referred to the 
K’ui-chéu schists, but in this northerly district metamorphism has been 
considerably more severe. Specimen from the summit of the first hill 
northwest of Liang-ho, Shen-si. 
An ocherous buff marble, the texture of which varies in different parts 
of the same specimen from fine-grained to rather coarse. Flakes of mus- 
covite and ferrite are scattered freely throughout the mass, but are espe- 
cially abundant along certain roughly parallel lamina. The rock is not, 
however, distinctly schistose. 
It is composed very largely of dull, cloudy crystals of calcite in which 
cleavage cracks are unusually prominent and closely spaced. In addition 
there are small crystals of quartz and muscovite which are scattered about 
without distinct orientation. Clouds of earthy limonite and other dark 
stains are prominent. There are also a few decayed scales of biotite, small 
crystals of tourmaline and apatite, and brownish grains of rutile. 
It is evident that this rock has entirely recrystallized. The muscovite 
is often inclosed in calcite and probably developed earlier than the latter. 
All of the quartz shows undulatory extinction, and thereby indicates that 
the rock has been subjected to severe strain since it attained its present 
condition. 
Gray micaceous marble, No. 116.—The same as No. 117. It is a gray 
sugary marble, indistinctly banded with a darker shade. Both light and 
dark micas are abundant along certain planes in the rock, but they are rare 
in other parts of the mass; the rock is, therefore, partially schistose. 
This variety so closely resembles the last in everything but color that 
it will be sufficient to mention simply a few points of difference. Unlike 
No. 117, this marble contains rather more biotite than muscovite, and the 
color is due to the presence of graphite instead of ferruginous matter. The 
biotite flakes are reddish-brown, the pleochroism varying to pale greenish. 
The flakes of this mineral are small and arranged in parallel sheets after the 
manner of schistose rocks in general. Some of them are bent and more or 
less crushed, evidently by movements which have taken place subsequently 
to the crystallization of the rock. The micas include minute crystals of 
zircon, tourmaline, and rutile. The alteration of the biotite produces a 
pale chlorite, and small grains of iron ore separate out during the process. 
Apparently this marble could have been produced from such a rock 
as No. 119 by more severe dynamic metamorphism. The calcareous 
portion of the rock has formed interlocking calcite crystals of considerable 
