450 RESEARCH IN CHINA. 
axes all parallel except where their arrangement is interfered with by the 
grains of quartz to which they are obliged to conform. 
Magnetite phyllite, No. 124.—The gray phyllite is one phase of the dark 
slates and limestones of the upper Han. Near Shi-ts’tian-hién it is inter- 
bedded between a dark gneissic magnetite-quartzite (No. 114) and black 
slaty limestones which include coaly strata. Specimen from a lateral 
ravine on the southwest side of the Han river, 3 miles, 3 kilometers, below 
Shi-ts’tian-hién. 
A lustrous gray phyllite through which are scattered medium-sized 
crystals of magnetite. It is a soft rock, but has good cleavage. 
The greater part of the rock is composed of finely crystalline quartz, 
together with abundant minute flakes of muscovite and chlorite, all of 
which lie with axes parallel to the cleavage of the rock. Certain thin bands 
have less mica than others, and so the slide presents a striped aspect not 
noticeable in the hand-specimen. Magnetite occurs in the form of large 
angular crystals and as swarms of small grains. These clusters of minute 
magnetites are closely associated with certain cloudy ocherous and greenish 
areas which appear almost isotropic between crossed nicols. This material 
is slightly fibrous, has a very low birefringence, and is probably chlorite dis- 
colored with earthy iron oxides. Various portions of the rock contain 
little prisms of tourmaline and grains of epidote. 
All of the constituents of the gray phyllite appear to be of secondary 
origin. The composition of the rock suggests that it was originally a ferru- 
ginous shale which has been deformed in the zone of anamorphism. Under 
mass-mechanical conditions,* the parallel seams of quartz and micas were 
produced. After this process had been concluded mass-static conditions fT 
seem to have prevailed; heavy silicates and oxides could then grow without 
regard to the previous structure of the rock and thus become porphyritic 
crystals. This probably is the origin of the few large scales of biotite and 
smaller muscovites, the little tourmaline prisms, and the large magnetite 
crystals, which lie at all angles to the schistosity and cut across the mica 
seams without disturbing their position in the least. In some cases the 
biotites are surrounded by areas poor in chlorite, limonite, and muscovite 
flakes, but rich in quartz; evidently the material for each large mica plate 
has been derived largely from the smaller minerals which formerly occupied 
the spot. 
PELITE (?) SCHISTS. 
In addition to the foregoing rocks, 7. e., the slates and fine-grained 
phyllite, there are certain varieties of schists which are known to be of 
sedimentary origin because they are interbedded with limestones and 

*Van Hise: A Treatise on Metamorphism, U. S. Geol. Surv. Monograph xLvn, p. 696. 
tIbid., p. 701. 
