国立情報学研究所 - ディジタル・シルクロード・プロジェクト
『東洋文庫所蔵』貴重書デジタルアーカイブ

ochreous yellow; Y and Z, deep sage green to black; most
commonly black. It includes some rounded crystals of
zircons. Pleochroic haloes were looked for, but none were
found.

A few rare crystals of other minerals are present, a little
apatite and zoisite. One elongated crystal of zoisite is
particularly interesting, since it has been broken across in
several places in the direction of pressure, i. e. at right angles
to the general parallelism, and one of the fractures has been
enlarged so as to produce a considerable interval which has
been filled by a growth of muscovite.

35. Pei-shan, C. 212 (06). *Quartz Schist.*
This is a small fragment of a compact rock and in the
hand specimen shows no signs of schistosity; under the
microscope, however, it is seen to be definitely foliated. It
consists chiefly of a quartz mosaic, the elements of which
show undulose extinction and are elongated in one direction,
as also are the other constituents of the rock. These consist
of muscovite and biotite, which are closely associated; indeed
the biotite appears to pass into muscovite. The biotite is

strongly pleochroic: X, faint brown; Y and Z, completely
absorptive, i.e. black, even in thin films. Felspars are
absent, but a rounded and broken grain of epidote is some-
times to be seen.

36. Nan-ch'üan, Pei-shan (04). Nineteen miles NW.
of Nan-ch'üan (9. ix. 1914). *Dolerite.*
A fragment of a dark grey rock; sp. gr. 2·95.
A thin slice presents plank-like and occasionally tabular
sections of Labrador felspar, often ophitic with augite. In
some cases the two minerals form roughly radiate inter-
growths, a rude attempt at a spherulite on a grand scale.
The labradorite is very much altered (sericitized?), and
loaded with the products of alteration, especially in the
middle, the margins alone remaining clear. There is a
singular rarity of albitic twinning. It often shows undulose
extinction. The augite is colourless, where fresh, but gives
rise by alteration to green chlorite.
Ilmenite occurs in abundance, sometimes as skeleton
crystals, but is not bordered by leucoxene.

EASTERN T'IEN-SHAN

37. Ümür-tägh. Cliffs in gorge sixteen miles NW. of
C. 218 (01). *Quartz Monzonite.*
Hypidiomorphic granular rock composed of orthoclase,
microperthite, albite and quartz, pyroxene, amphibole, biotite,
apatite, titaniferous magnetite, sphene, and rare zircons.
The apatite and no doubt the zircons were the first to
crystallize out, then followed the titaniferous magnetite, which
includes apatite and is corroded by quartz. This mineral is
bordered by colourless transparent sphene. The pyroxene—
a colourless diopside with diallage structure—next made its
appearance; it rarely or never presents crystal outlines, owing
to the transformation of its outer part into a green hornblende,
which presents the following pleochroism: X, colourless or
faint yellowish green; Y, deep green, occasionally bluish
green; Z, green or bluish green; and extinguishes at a high
angle, as much as 25°: it closely resembles Hastingsite.
The biotite, at least in part, is later than the hornblende;
in one instance it includes a corroded crystal of hornblende
which itself encloses a core of augite. It occurs in rather
large crystals, brown when fresh (green when altered), and
strongly pleochroic: X, clear yellow; Y and Z, deep brown.
A good deal of apatite, sometimes in unusually large crystals,
is included in the biotite, but no zircons. The only zircon
observed was in quartz.
The felspars followed the biotite, and the orthoclase the
albite which occurs in idiomorphic hypidiomorphic crystals,
sometimes corroded and embedded either in orthoclase or
quartz. The orthoclase and microperthite form large hypidio-
morphic crystals.
The quartz, which was the last to consolidate, is interstitial;
it has acted as a corrosive solvent on most of the other
minerals.

Some secondary sphene and calcite are present in the rock.
38. Ümür-tägh. From big rock wall, six miles NW. of
C. 218 (02). *Pegmatitic Granite.*
Coarse pegmatitic granite with red felspar, chiefly ortho-
clase of sp. gr. 2·55. Sp. gr. of rock, 2·61.
39. Ümür-tägh. Thirteen miles NW. of C. 218 (03).
*Granophyre.*
A fragment of a brownish-grey fine-grained rock with
numerous internal close fractures.
It consists of a micrographic growth of quartz and ortho-
clase; primary ferro-magnesian minerals are absent, but are
represented by some rare sporadic crystals of epidote.
The micrographic or micropegmatitic material has been
deformed by pressure and in many cases sheared into phacoids
which are sometimes well defined by thin lines of an opaque
white substance which appears to be altered epidote.
The thread-like rays of the micrographic radioles have
been bent out of their original course, quartz grains have
been crushed along the margin and reconstituted: they show
undulose extinction, and this is represented in the felspar
crystals by irregular bands crossing a section, which extin-
guish at a slightly different angle from the rest of the crystal.
A general parallelism of structure has been impressed upon
the rock.
40. Ümür-tägh. From a decayed ridge, nine miles NW.
of C. 218 (04). *Arcalite (Aplite).*
A salmon-red rock composed almost entirely of quartz and
felspar. The quartz is dusty with vapour cavities and unde-
termined particles. The felspar is orthoclase, microcline, and
albite in hypidiomorphic crystals.
Some altered biotite, corroded by quartz and associated
with sphene, is also present as well as a little magnetite.