372 RESEARCH IN CHINA. 
Much the larger part of this rock is made up of quartz and the alkali 
feldspars, orthoclase, microcline, and albite. The darker colored minerals 
are for the most part biotite and secondary epidote. As accessory minerals 
there are also present zoisite, muscovite, chlorite, apatite, rutile, zircon, 
and iron ores. 
The orthoclase and the albite crystals are considerably altered, being 
filled with small inclusions which appear to be for the most part muscovite 
and zoisite. The small crystals of microcline, however, which occur on 
the borders of these decayed feldspars, in association with micropegmatite 
and recrystallized quartz, are always fresh. 
The olive-brown biotites occur mainly in small disconnected wisps 
which are roughly parallel to the trace of banding in the rock. The par- 
tial alteration of this biotite has produced chlorite and perhaps epidote 
zoisite. The greater part of the epidote in the rock occurs in streaks, 
associated with muscovite, hematite, shreds of biotite, and bits of rutile 
which have probably been derived from the simultaneous decay of the 
feldspars and ferro-magnesian minerals. 
Originally this granite was probably composed of quartz, orthoclase, 
albite, and biotite, with a few rarer minerals. Changes which must have 
taken place under deep-seated conditions, and others which characterize 
the zone of fracture, have more or less changed these components and 
have developed new minerals out of the old material. 
In the zone of anamorphism, heavy stresses caused the granulation and 
recrystallization of a part of the rock, particularly in certain narrow zones. 
This produced fine-grained streaks of quartz and microcline crystals with 
roughly parallel micas of secondary origin. At this time also the epidote 
and most of the other secondary minerals were probably produced and 
were grouped in the seams in which they now appear. 
The subsequent changes occurring above the zone of flowage have 
been slight. Chlorite began to develop out of biotite and some slight 
advance was made in kaolinization of the feldspars, but the results are 
small. 
Red gneissoid granite, No. 32.—This is one of the darker phases of the 
granites which have been intruded into the older gneisses and schists in the 
T’ai-shan complex. Specimen collected along the great stairway up the 
T’ai-shan, at an elevation of 4,600 feet, 1,400 meters, above sea-level. 
The rock is similar to the last, but presents details worthy of special 
notice. 
Both the potash and the soda feldspars have developed microcline 
twinning. This feature frequently appears in only a portion of the crystals, 
while the remainder retains its original character. As a rule the albites 
