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

by the green variety which marks its first stage of alteration;
but these are almost constantly associated with an abundance
of colourless epidote and muscovite, the products of its
complete transformation.

Zircons are rare, but when present in the biotite are
surrounded by a faint pleochroic halo, the radius of which
does not exceed ·017 mm.

From Sai, six miles SSE. of C. civ; strike ESE.-

WNW., dip 75° NE. (012 and 015) quartz; (013) quartz
schist, no doubt part of a mica schist series; (014) granite.

12. Near dry river-bed of Kuruk-daryā. Aplite ?
A small worn angular fragment of a red quartz felspar
rock.

12 a. Kum-Kuduk, 8 miles NW. of. Rock-salt.
Irregular nodules, some consisting of rock-salt encrusted
with sand, some of sand cemented with rock-salt.

TERMINAL COURSE OF ETSIN-GOL RIVER

13. Mao-mei (01). Hornblende Andesite.
A closely jointed dark grey, almost black, rock with small
phenocrysts. Sp. gr. 2·73.

The ground mass is difficult to analyse: it consists of
irregular areas of felspar crowded with minute granules and
needles, some if not all of which are hornblende.

The phenocrysts are idiomorphic crystals of hornblende,
plagioclase, and magnetite. The plagioclase is glassy clear,
often either zonal, or with undulose extinction. Its optical
properties and specific gravity show that it ranges from
andesine to labradorite.

The hornblende is defined by the forms (110), (010), and
(100); it extinguishes at 19° and its pleochroism is, X, from
colourless to faint yellow; Y, brown; Z, also brown, but of
a darker shade.

Biotite is represented by a few rare phenocrysts which
present reaction rims of hornblende and magnetite. In one
case biotite forms the core of a crystal of plagioclase and
some of its cleavage lamella penetrate the felspar running
parallel to the planes of albitic twinning.

Apatite is fairly abundant, especially in association with the
biotite: some sphene is present and a little, almost colourless
but slightly pleochroic, epidote.

14. Mao-mei (02). Granite.
A rather coarse reddish, consisting of a mosaic of quartz,
hypidiomorphic crystals of felspar, biotite, and muscovite.

The quartz contains abundant liquid cavities, isolated
fragments of biotite, muscovite often in small crystals which
may be grouped in clusters, and numerous granules which
appear to be the remains of some incompletely digested
mineral, probably felspar. The liquid cavities form long
linear series which run in one prevalent direction and some-
times cross from one element of the quartz mosaic into
another.

The felspar consists of orthoclase, more or less perthitic,

microcline, and a plagioclase which appears to be an albitic
oligoclase.

The biotite is brown and strongly pleochroic: X, straw
yellow; Y and Z, deep brown to black. It contains crystals
of zircon and apatite; the former surrounded by pleochroic
haloes.

The muscovite is both primary and secondary. When
primary it sometimes corrodes the biotite and completes its
growths, the cleavage planes of the two maintaining a strict
parallelism.

14 a. (03). A worn fragment. Quartz.

15. Mao-mei (04). Quartz Hornblende Schist.
This well-foliated green schist consists of quartz mosaic,
plagioclase felspar, and parallel foliae of hornblende. Asso-
ciated with the hornblende here and there is a brown biotite, the
cleavage planes of which also lie approximately in the plane
of foliation. A good deal of apatite, magnetite, and some
isolated crystals of epidote are also present.

The hornblende is grass green in colour and strongly
pleochroic: X, faint straw yellow; Y, dark green; Z
greenish blue. Its angle of extinction is 24°.

The pleochroism of the biotite is, X, faint yellow, like the
hornblende; Y and Z, deep brown.

The quartz mosaic includes abundant andesine in individuals
which sometimes acquire a comparatively large size. In
some cases the felspar is shot through with threads of quartz.
The apatite also occurs in large crystals or rounded grains.

The eyes formed by an expansion of the clear quartz
mosaic resemble those described later in the hornblende
schist (72) of Mīrān, but contain in some cases as an additional
mineral a faintly pleochroic almost colourless epidote. It
often lies in the middle of an eye and is bordered by a
fringe of small fragments which have been detached from it.
In some cases a whole crystal has been resolved into a heap
of small grains.

PEI-SHAN RANGES

16. Chin-êrh-ch'üan, Pei-shan (013). NW. of Ming-
shui, from ridge one mile SE. of Chin-êrh-ch'üan.
Brecciated Rhyolite.
A compact, jointed, chocolate-coloured rock with small
lighter coloured inclusions. The joint surfaces are covered
with a black lustrous patina.

It consists of a finely granular, colourless, glassy basis,
through which are scattered angular fragments and splinters
of quartz, broken crystals of orihoclose, and oligoclase.
Immersed in this are small fragments of rhyolite with marked
flow structure. These, which are themselves fractured, and
differ in details from one another, form the greater part of

II 6 U