358 RESEARCH IN CHINA. 
KHIN-GAN DISTRICT. 
While crossing the Khin-gan range, in northwestern Manchuria, on 
the Chinese-Eastern (Trans-Siberian) railroad, we observed, in a very 
casual way, something of the geological formations there exposed. Inas- 
much as the party did not stop to undertake field-work on this part of 
the journey, the Khin-gan district, so called, will be understood to include 
only that portion of the range which can be seen directly from the railroad. 
Rocxs OF IGNEOUS ORIGIN. 
The rocks of the Khin-gan district appear to be very largely igneous. 
In addition to the granite, which is described below, igneous rocks in con- 
siderable variety were observed in the gravel which covers the valley-floor 
near Barim. Among these were black quartz porphyry, purplish and 
flesh-colored hornblende porphyries, feldspar porphyry, and gray horn- 
blende granite. Nothing was learned regarding the occurrence and rela- 
tionships of these rocks, but it is evident that all of them outcrop in the 
valleys of this stream or its tributaries. 
Gray biotite gramte, No. 1.—This granite forms the axial portion of 
the Khin-gan range, at the point where it is crossed by the Chinese-Eastern 
railroad. Although limestone and other rocks of sedimentary origin occur 
at no great distance to the westward, it was not practicable to ascertain 
the relation which the granite bears to these and to other igneous rocks 
of the region. Specimen taken on the east side of the Khin-gan pass 
400 feet, 120 meters, above the tunnel. 
The rock is rather coarse-grained and shows only a trace of gneissic 
banding. ‘The more abundant minerals are quartz, microcline, and plagio- 
clase, with lesser amounts of orthoclase and biotite. Among the accessory 
minerals which occur in small quantity are hornblende, titanite, magnetite, 
apatite, tourmaline, and zircon. 
The quartzes are pale smoky in color with a faint tinge of violet. They 
include an abundance of hair-like crystals, or trichites, probably rutile. 
Microcline, the most abundant feldspar, occurs in rather large white 
crystals, which have suffered but little alteration. Incipient decay into 
kaolinic material develops first along certain of the twinning lamella, giving 
the feldspar a streaky appearance in ordinary light. Although the flesh- 
colored orthoclase occurs in large crystals, it is the least abundant of the 
feldspars. Like the microcline, it is comparatively little altered chemically. 
The plagioclase is a sodic feldspar which probably has the composition of 
oligoclase. ‘That it began to crystallize earlier than the other feldspars is 
indicated by the fact that it frequently occurs in idiomorphic crystals, often 
twinned according to the Carlsbad law. In contrast to the potash feld- 
spars, these plagioclases have suffered extensive alteration into saussurite. 
