448 RESEARCH IN CHINA. 
The rock has been folded and sheared in the greatest minuteness. 
In the thin section the parallel folds and overthrusts are made conspicuous 
by the fact that the black graphite is concentrated along these lines (Plate 
LVI, Fig. E). Wherever the folds have been actually ruptured the breaks 
have been healed by the deposition of secondary quartz, and in these same 
areas other minerals, such as chlorite, sericite, and micaceous hematite 
have also appeared. Original sand-grains of quartz have been fractured, 
sliced, or otherwise deformed. Magnetite, however, seems to have resisted 
the crushing better than the quartz and usually occupies eye-spots, the 
corners of which are filled with secondary crystals of the latter mineral. 
Green nodular slate, No. 141.—The hard green slates are best exposed 
in the region of numerous landslides and gabbro intrusions south of Pai- 
kiu-hia. The formation is the equivalent of the green Sin-t’an shales of the 
Yang-tzi district. Specimen taken from landslide debris 3 miles, 5 kilo- 
meters, south of Pai-kiu-hia. It probably came from the broad contact 
zone bordering one of the basic intrusions of the locality (see No. 142). 
This well-cleaved green slate is hard and brittle. The original bedding 
is indicated by alternate light and dark-colored bands and by frequent 
seams of little blackish nodules. The slaty cleavage makes an angle of 
about 35° with this bedding plane. 
The mass of the rock is exceedingly fine-grained. It consists of quartz 
and probably feldspar, with flakes of micaceous minerals and a dust-like 
material of a darker color. From the parallel extinction of the mica- 
flakes they are thought to be sericite.* A parallel orientation is notice- 
able among these scales of mica. 
The dark nodules which were mentioned in the last paragraph do not 
show, in the thin section, exactly what their origin may have been. They 
appear to be composed entirely of fibrous green chlorite through which 
are scattered numerous transparent inclusions most of which are probably 
quartz. They are ill-defined in outline, exhibit no definite crystal form, and 
the ends are usually rounded or ragged. Inspection of the slide shows 
that these fragments have been fractured and the fragments somewhat 
displaced, the matrix in some cases having been sheared past the ends of 
the grains. On the frayed edges of the grains the chlorite is minutely 
shredded and intermingled with the sericitic ground-mass of the slate. 
No satisfactory interpretation of the nature of these bodies has been 
worked out. It has been suggested that they represent sand-grains of 
some ferro-magnesian mineral, which have since been completely altered 
to chlorite and quartz, and have been subsequently mashed and sheared 
until they have assumed their present outlines. In this case, however, 

*Michel Lévy and Lacroix: Les Minéraux des Roches, p. 253. 
