452 RESEARCH IN CHINA. 
The section is traversed by several micro-shear-zones filled with a 
black coloring matter which may well be graphite. 
Silvery mica schist, No. 118.—This is one of the harder phases of the 
abundant mica schists in the vicinity of Liang-ho. The schists are asso- 
ciated with thin layers of gray schistose marble.* The specimen is so 
nearly identical with the similar rocks in the canyon of the Han river near 
Shi-ts’tian-hién that there can be but little doubt as to the equivalence of 
the two formations. 
Specimen obtained about 1 mile south of Liang-ho on the trail lead- 
ing southward to Shi-ts’tian-hién. 
This rock is similar in many ways to No. 123, and is evidently a part 
of the same terrane. The schistosity is, however, more perfect; and in 
addition to the flakes of biotite there is a great abundance of finely divided 
muscovite, which gives the rock its silvery sheen. Upon close examination 
it is possible to distinguish a few small pink garnets. 
Thin sections resemble those of No. 123 very closely, except that the 
quartz is somewhat coarser grained and the plates of biotite average larger. 
In describing this variety it will not be necessary to repeat those details 
in which it agrees with the rock last described, but it will be sufficient to 
mention its individual peculiarities. 
In the section the garnets (almandine?) are seen to be very irregular 
and ragged in outline. As usual they appear to have developed under 
mass-static conditions subsequent to the development of the schistosity, 
and as they grew in the rock they included many bits of quartz, magnetite, 
etc. A katamorphic alteration of the garnet to chlorite has begun along 
the numerous cracks in the mineral. Staurolite occurs in crystals quite 
as irregular as those of the garnet, but it is a somewhat rarer mineral. 
The variety here represented is yellow and exhibits no reddish pleochroism. 
In addition to the more abundant minerals a few small crystals of 
ilmenite and pale-brown tourmaline were observed. 
Like No. 123, this mica schist is a completely recrystallized sediment- 
ary rock. Since the recrystallization and adjustment, which took place 
under mass-mechanical conditions in the zone of anamorphism, certain 
porphyritic minerals, such as garnet, staurolite, biotite, and tourmaline, 
have grown in the midst of the schistose mass. At a still later period there 
has been a certain amount of mechanical deformation which has left its 
impression in some of the biotite crystals, which are bent and faulted. 
This, however, seems to have been an episode of minor importance in the 
history of the rock. 
*See Nos, 116 and 117. 
