Appendix O] SPECIMENS OF ROCK AND SAND 1075
Sand from Camp ccxl a, NE. of Chainut•köl (29. D 4).
Fine light grey powder with grains less than •2 mm., and with irregular aggregates up to 10 mm. long and gypsum crystals.
The gypsum crystals contain so much of the powder as to be quite opaque, and the aggregates consist of the powder cemented by gypsum. Of the heavy minerals, biotite and green amphibole are abundant and apatite is'common.
Sand, thirteen miles SW. of Camp ccxxxviii a, E. of iiltmish-bulak (32. B 3).
Fine light grey powder, less than •2 mm. in diameter, with aggregates and gypsum concretions up to 5 mm. and well-rounded grains up to 3 mm.
The aggregates consist of grains of the powder cemented by gypsum. The large grains include turbid felspar, and quartz with many composite grains. Colourless and green amphiboles are abundant. Of the heavy minerals, biotite and muscovite are common. Gypsum is very abundant in the fine powder, and there is some salt.
Soil with gypsum and ' shôr', eight miles SE. of Camp ciii, Lop Desert (32. B 3).
Fine light grey powder less than •2 mm., with aggregates up to io mm., corroded gypsum crystals up to 3o mm. long, and well-rounded grains from •5 mm. to 5 mm. in diameter.
The powder contains a little calcium carbonate, abundant gypsum, and some salt, and green amphibole is abundant in the heavy crop.
There is quartz, in addition to composite grains, among the large grains.
Drift-sand on Sai of Kuruk•tâgh, 121 miles E. of Camp ciii, Lop Desert (32. C 3).
Coarse, multicoloured sand, with many well-rounded grains, ranging from •7 mm. to 2 mm., very few grains less than •7 mm. in diameter, and irregular gypsum concretions up to 5 mm.
There are no simple heavy minerals ; most of the grains are fine grained and indeterminate, but there is a good deal of quartz, with some red felspar and fine-grained quartzite.
Coarse sand from eroded Nullah, three miles SSE. of Camp civ, Lop Desert (32. C 3).
Well-rounded, multicoloured sand, with grains ranging from i mm. to 4 mm. in diameter. Coloured grains are more numerous than colourless. The most abundant type is a fine-grained dark grey or purple grit. Quartz, quartzite, and gypsum concretions are common.
Coarse sand from vegetation belt, five miles NNE. of Yantak-kuduk (35• A 4).
Coarse, multicoloured sand, with the smaller grains well rounded and the larger generally subangular.
.7 mm. •7-5 mm.
Mechanical analysis : 2 % 98
The smaller grains are mainly composite, but there is some quartz, turbid felspar, and calcite. The larger grains
are very varied, and include red granite (with turbid felspar), light green amphibole schist, fine-grained white limestone, fine-grained quartz and felspar rock, red and purple; fine-grained rock containing much felspar (R.I. < 1.536).
Sand from ridge of dunes, 25'-30', crossing terminal basin of Su-to-ho, five miles from Camp cxii (35• C 4).
Well-rounded, multicoloured sand, ranging up to 1.5 mm. <•2 mm.- •2-•4 mm. •4-•7 mm. >•7111111.
Mechanical analysis : r % 7 % 39 % 53
Composite grains predominate. In the heavy crop pink garnet is abundant, and hypersthene, epidote, and green amphibole are common.
Sand from hillock, 8', in terminal basin of Su-to-ho, nine miles E. of Besh•toghrak (35. B 4). Well-rounded, multicoloured sand, ranging up to 2 mm. < •2 mm. •2-•4 mm. •4-•7 mm. > 7 mm.
Mechanicalanalysis: 13% 2o% 45% 22%
Composite grains are predominant and simple heavy minerals are scarce, but there are a few grains of green amphibole. Felspars are abundant.
Sand from moist lagoon bottom of Su-lo-ho terminal basin, seven miles E. of Besh•toghrak
(35. B 3).
Well-rounded, light brown sand, with many coloured grains.
< •2 mm. •2-•4 mm. •4-•7 mm. > •7 mm.
Mechanical analysis: 13 % 40 % 42 % 5
Light-coloured opaque grains form the bulk of the heavy crop, but green amphibole, magnetite, and garnet are common.
Coarse gravel and sand overlying clay at foot of Sai, near N. edge of Mesa area, terminal basin of Su-lo-ho, fifteen miles E. of Bésh-toghrak
(35 C 4)•
Well-rounded, multicoloured sand, ranging up to 2 mm., with a large number of subangular pebbles ranging from 5 mm. to 15 mm.
Mechanical analysis : 12 % 36 % 52
There are no simple mineral grains in the heavy crop.
The pebbles include pink granite with turbid felspar, fine-grained brown grit, fine-grained light green amphibole + felspar rock, and rhyolite showing granophyric structure.
137. Sandy stratum in clay ridge, zoo', fourteen miles E. of Besh•toghrak (35. C 4).
Well-rounded sand with a good deal of light brown mud, which coats the grains and sometimes binds them into loosely cohering aggregates. The grains range in size between .7 mm. and 3 mm., the bulk being from r mm. to 1.5 mm. in diameter.
The only simple mineral grains seen in the sand are quartz, felspar, and garnet ; in the mud, quartz, felspar, mica, and calcite were identified.