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

an irregular mosaic of calcite, the individual crystals of which
measure about ·04 to ·06 mm. in diameter, and minute
granules or rhombohedra also of calcite, but measuring from
·007 to ·012 mm. in diameter.

Some small opaque cubes, rusty red by reflected light, are
scattered here and there ; some are surrounded by a brownish
halo. They appear to be oxidized pyrites.

On solution in hydrochloric acid an odour of petroleum is
given off and a black dust of carbonaceous matter is left as
a residue. On examining this under the microscope a small
quantity of mineral matter is found to accompany it. The
greater part consists of minute granules, many no more than
·0037 mm. in diameter. They are colourless and trans-
parent : some are found united in various ways, two combine
to form a rod, or three or more are joined together and from
these complexes crystals are built up, some with well-defined
and continuous outlines, but hollow in the middle ; others,
finally, are fully completed forms. The specific gravity of
this material was found to lie between 2·55 and 2·57, the
refractive index a little above 1·5. One or two larger
crystals measuring ·04 by ·08 mm. were observed which
closely resembled a common form of sanidine, and there can
be no doubt that the whole of this material is orthoclase. The
first impression produced when studying it is that it presents
us with the various stages of growth from granules com-
parable with the globulites of Vogelsang up to the completed
crystal, but on reflection another explanation appears to be
possible ; the incomplete forms may not be the germs of
crystals but the products of their dissolution, and this view is
sustained by the presence of other minerals undoubtedly
foreign to the rock, such as minute scales of muscovite and
grains of quartz. This conclusion, if correct, has an obvious
bearing on the supposed presence of primary albite in
metamorphosed limestone.

28. Ta-shi-kou, Pei-shan. Epidote Rock.
A much-jointed fragment of an apple-green rock, contain-
ing obvious quartz.

The greater part of the rock is an aggregate of granular
crystals of epidote ; it is traversed by numerous cracks running
in various directions and now healed-up vein deposits. The
rock has evidently been brecciated in place, but in addition
movement has taken place along some of the fractures.
Phacoids of another rock, retaining their original composition,
are distributed along these fractures.

The phacoids consist of coarse quartz mosaics, showing
undulose extinction, and large crystals of albite which are
traversed by fractures and faults and otherwise deformed,
as is shown by the curvature of the twinning planes and
the production of secondary twinning which crosses the
original.

29. Yeh-ma-ching, Pei-shan (01–06). Dolomite.
Fragments of pink compact dolomite traversed by veins of
calcite and quartz and worn by the wind so that the quartz
veins stand out in relief.

The rock is a very fine-grained aggregate of minute

crystals of colourless dolomite and granules of quartz, crossed
by fine veins of quartz and calcite.

The granules of quartz when set free by solution are
found to be coated with red oxide of iron, which dissolves
with difficulty in nitro-hydrochloric acid.

30. Yeh-ma-ching, Pei-shan (07). Four miles S. of
Yeh-ma-ching. Grey Grit.
A light grey laminated grit composed chiefly of rounded
and angular grains of quartz and sericitized felspar, with
some muscovite and chlorite. Some of the quartz grains are
composite and might have been derived from a granophyre.

Calcite is present, chiefly as a secondary constituent.

31. Yeh-ma-ching, Pei-shan (08). Red Grit.
A fine-grained purple grit very similar to No. 30. There
is a noticeable quantity of fresh felspar, some of which is
orthoclase, but the greater part albite or oligoclase. Iron ore
is abundant and pyrites occur in small quantity. There is
also a good deal of secondary calcite.

32. Pei-shan. Ridge flanking valley two miles NW. of
C. 209 ; dip 82° SE., strike NE.–SW.
Fine-grained grit consisting chiefly of quartz ; there is a
little felspar, some of which is andesine, also grains of calcite
and needles of mica which are scattered throughout. The
rock is traversed by thin veins of calcite, haematite, and
quartz.

33. Pei-shan, C. 210 (04). Amphibolite.
A compact non-foliated dark green rock.

This consists of a fine mosaic of quartz, through which are
scattered in all directions long blades of green hornblende
and flakes of brown biotite.

The hornblende extinguishes at 20° and is strongly
pleochroic : X, pale straw colour ; Y, deep green ; Z, greyish
blue. It is riddled with quartz, to which are also due its
ragged margins.

The biotite, which is sometimes, but not always, intimately
associated with the hornblende, is also strongly pleochroic :
X, pale yellow ; Y and Z, deep brown. Some plagioclase
felspar (andesine) contributes to the quartz mosaic.

Magnetite is fairly abundant ; apatite and zircons are also
present, the latter surrounded by a pleochroic halo in the
biotite which contains them.

Some thin veins of calcite traverse the rock.

34. Pei-shan, C. 212 (06). Quartz Mica Schist.
A pebble of a compact greenish rock.

The greater part of the rock is formed by a mosaic of
quartz with its components all elongated in one direction.
Running parallel with them are flakes of muscovite and
subordinate biotite, either as single crystals or in long trains.

The muscovite is closely connected with the biotite and in
some cases can be traced into apparent continuity with it :
thus a long transverse section of a muscovite cleavage lamella
may be completed by biotite, and when the biotite is so
orientated as to appear colourless no distinction can be dis-
cerned between the two parts of the section.

The biotite is strongly pleochroic : X, colourless to faint