432 RESEARCH IN CHINA. 
Massive greenstone, No. 94.—A dike of this rock 60 feet, 18 meters, thick 
cuts the garnet schists at Shang-ho-miau (Plate XVIII, stratum 22). Ata 
short distance the appearance of the intrusion suggests a basalt dike of 
recent origin, but closer study shows that the rock is completely metamor- 
phosed. 
A greenish-black massive rock of fine texture. It is composed of 
interlaced fascicules of hornblende mingled with limpid quartz and feldspar. 
The latter, being transparent, exert little influence on the color of the mass. 
In the thin section a rude parallelism of the hornblendes is apparent, but 
the structure is not sufficiently prominent to induce schistosity. 
Recrystallization under anamorphic conditions has been complete, 
leaving no traces of original structures or minerals. More recently changes 
have taken place in the zone of fracture, resulting in the formation of 
chlorite from the amphibole and of micaceous material in the feldspars. 
The irregular bodies of ilmenite and pyrite are not visibly altered. 
Schistose greenstone, No. 89.—Like the last this greenstone occurs as a 
dike in the walls of the T’ai-shan-ho canyon. ‘The intrusion has a thickness 
of about 30 feet, 9 meters, and rises vertically through mica schists of the 
Shi-tsui series, 2 miles, 3 kilometers, northwest of Shi-tsui. A vein of 
hornblende-feldspar pegmatite emanates from the dike as if it had been 
an original apophysis from it. 
The rock resembles No. 94 so closely that a brief description of differ- 
ences will suffice in this case. The specimen is distinctly schistose and 
the thin section shows that the hornblende crystals lie in thin parallel 
lamine alternating with streaks composed of the quartz and feldspar. ‘The 
iron ores are less abundant, but granules of epidote and sphene, not observed 
in No. 94, are present here. It seems not improbable that the streaks of 
granular titanite may be secondary alteration products of original ilmenite. 
ActbD PORPHYRIES. 
Gray rhyolite porphyry, No. 93.—A few small dikes of quartz porphyries 
cut the quartzites and schists about 4 miles, 6.5 kilometers, northwest of 
Shi-tsui. From their similarity to dikes elsewhere which have intruded 
the Sinian strata we infer that they are likewise of post-Sinian age. 
Our specimen is extensively decayed. In the gray surfaces one may 
detect a few phenocrysts of quartz, pink feldspar, and rarely magnetite. 
The quartzes are prominently idiomorphic and the pyramidal terminations 
may be clearly seen with a hand-lens. Under the microscope the felds- 
pathic phenocrysts appear to consist largely of a micropegmatitic inter- 
growth of quartz and alkali feldspar. All of these crystals are bounded 
by opaque reaction rims and many are deeply corroded. 
