Geological researches in China, Mongolia, and Japan, during the years 1862-1865.

CHINA, MONGOLIA, AND JAPAN. 37
Hiangshui (pu), and also in the coal field of Kiming, where they occur apparently
as members of the coal-bearing series, and at a higher level than the lower coal
seams.
The fragments of porphyry that form the characteristic feature of this deposit,
have a base that varies in texture, from compact to finely crystalline, in color from
dark reddish-brown to black, and that effervesces slightly in dilute muriatic acid.
It contains numerous thin, oblong crystals, of a white triclinic feldspar, from oneeighth to three-quarters of an inch long. Through the base are scattered grains
of a white mineral, apparently a zeolite, and scales of what seems to be ichthyophthalmite.
In places, these fragments make up the greater part of the deposit, and it is then
difficult to distinguish the inclosed from the inclosing rock. In other places the
blocks are scattered through a finely crystalline, dark reddish-brown rock, that is
irregularly impregnated with a carbonate, and about as hard as compact limestone.
It contains also pieces of an amygdaloidal rock, the cells of which are filled with
calcite and a white zeolite; blocks of limestone are also found in it.
The general appearance and manner of occurrence of this deposit suggests the
idea that it is of pluto-neptunian origin, and perhaps contemporaneous with the
eruption of the greenstone-porphyry. I will add that I did not meet with dykes
of this porphyry.
Kalgan Trachytic Porphyry.-This rock, and its pluto-neptunian deposits form
the hills around Kalgan, and those that, extending S. E. from that city, send out a
spur to the west crossing the road from Siuenhwa.
The porphyry in question is very variable in color, the most common variety
being brown, but all shades occur from pitch-black to white, red, and green. The
texture of the rock is compact, often almost vitreous, but in structure it ranges from
the solid rock of the Kalgan mountain to the cellular and often almost pumiceous
variety of the spur between Kalgan and Siuenhwa.
Crystals of white, transparent orthoclase, or glassy feldspar, are always present,
and are generally so limpid as to take the color of the variety in which they are
imbedded. Small grains of pellucid quartz occur more rarely, but seem in places
to belong to the primary ingredients, though they are generally secondary. Mica
and hornblende are always absent.
The cells are sometimes long-cylindrical, but more generally flattened, though
lying in the same direction. They are filled with different varieties of quartz, as
cornelian, chalcedony, and a'black sllex. More rarely they are filhle with calclte.
The base of this rock fuses easily before the blowpipe to a white vesicular glass
on the edges.
In intimate connection with this porphyry are strata'of a deposit which, from
their character and manner of occurrence, appear to be of pluto-neptunian origin,
and were probably formed contemporaneously with the eruption of the porphyry.
These consist chiefly of a tufa, varying in color from white and gray to purple, and
in hardness between that of chalk and limestone. Its texture is rough and earthen
in appearance. Through the mass are scattered crystals of glassy feldspar, grains
of limpid quartz, and hexagonal scales of dark-brown mica.