<table>
<colgroup>
<col style="width: 2%" />
<col style="width: 2%" />
<col style="width: 2%" />
<col style="width: 4%" />
<col style="width: 7%" />
<col style="width: 5%" />
<col style="width: 4%" />
<col style="width: 3%" />
<col style="width: 3%" />
<col style="width: 4%" />
<col style="width: 5%" />
<col style="width: 4%" />
<col style="width: 7%" />
<col style="width: 5%" />
<col style="width: 4%" />
<col style="width: 3%" />
<col style="width: 16%" />
<col style="width: 8%" />
<col style="width: 4%" />
</colgroup>
<tbody>
<tr class="odd">
<td><strong>Map Row</strong></td>
<td><strong>Map Col-umn</strong></td>
<td><strong>No.</strong></td>
<td><strong>Latitude, DMS</strong></td>
<td><strong>Latitude, DD</strong></td>
<td><strong>Longitude, DMS</strong></td>
<td><strong>Longitude, DD</strong></td>
<td><strong>Major Commod-ities</strong></td>
<td><strong>Minor Commod-ities</strong></td>
<td><strong>District Name</strong></td>
<td><strong>Deposit Type</strong></td>
<td><strong>Deposit Size</strong></td>
<td><strong>Grade</strong></td>
<td><strong>Tonnage</strong></td>
<td><strong>Fineness</strong></td>
<td><strong>Years of Produc-tion</strong></td>
<td><strong>Summary</strong></td>
<td><strong>References</strong></td>
<td><strong>Country</strong></td>
</tr>
<tr class="even">
<td>H</td>
<td>52</td>
<td>01</td>
<td>31 16 01N</td>
<td>31.2669444444444</td>
<td>130 37 57E</td>
<td>130.6325</td>
<td>Fe</td>
<td>Ti</td>
<td>Ibusuki</td>
<td>Placer Fe</td>
<td></td>
<td>Average grade of 22% Fe and 3.7% TiO2.</td>
<td></td>
<td></td>
<td></td>
<td>Consists of a large number of placer deposits along beach. District
is 60 km long on Satsuma Peninsula side, and 20 km long on Osumi
Peninsula side around Kagoshima Bay. Eight subdistricts occur in the
district. Placer Fe minerals occur in modern beach sands. Thickness of
deposits are 0.05 to 0.2 m. Ore minerals are magnetite, hematite, and
ilmenite.</td>
<td>Geological Survey of Japan, 1954.</td>
<td>Japan</td>
</tr>
<tr class="odd">
<td>I</td>
<td>52</td>
<td>01</td>
<td>33 36 12N</td>
<td>33.6033333333333</td>
<td>131 42 37E</td>
<td>131.710277777778</td>
<td>Fe</td>
<td></td>
<td>Kunisaki</td>
<td>Placer Fe</td>
<td></td>
<td>Average grade of 15% Fe.</td>
<td></td>
<td></td>
<td></td>
<td>Consists of 13 main placer deposits along a beach. Main part of the
district is about 30 km long in the Kunisaki Peninsula, Oita Prefecture.
Major deposits are at Yasugahama and Tomiku. Placer Fe minerals occur
modern beach sands. Thickness of deposits is 0.1-0.2 m. Ore minerals are
magnetite and ilmenite.</td>
<td>Geological Survey of Japan, 1954; MITI, 1959, 1959; Hasegawa,
1963.</td>
<td>Japan</td>
</tr>
<tr class="even">
<td>I</td>
<td>53</td>
<td>01</td>
<td>35 41 57N</td>
<td>35.6991666666667</td>
<td>140 42 05E</td>
<td>140.701388888889</td>
<td>Fe</td>
<td>Ti</td>
<td>Iioka</td>
<td>Placer Fe</td>
<td></td>
<td>Average grade of 10.4% Fe and 2.4% TiO2</td>
<td></td>
<td></td>
<td></td>
<td>Consists of two major placer deposits along beach. District is about
10 km long and 1 km wide. Each body is 3 km long, 70-100 m wide, and
2-10 m thick. Four major mines are in the district. Placer Fe minerals
occur in coastal plane deposits, coastal terrace deposits, and modern
beach sands. Fe minerals in a coastal plane deposits is major type in
the area. Sands contain magnetite, hematite, ilmenite, pyroxene, quartz,
and plagioclase.</td>
<td>Geological Survey of Japan, 1954.</td>
<td>Japan</td>
</tr>
<tr class="odd">
<td>I</td>
<td>53</td>
<td>01</td>
<td>35 26 51N</td>
<td>35.4475</td>
<td>133 17 30E</td>
<td>133.291666666667</td>
<td>Fe</td>
<td>Ti</td>
<td>Yonago</td>
<td>Placer Fe</td>
<td></td>
<td>Average grade of 24% Fe and 3.2% TiO2.</td>
<td></td>
<td></td>
<td></td>
<td>Consists of a large number of placer deposits along a beach that is
80 km long from Tottori to Yonago. Major deposits are at Yonago,
Takaraki, Hamamura, and Kaike. Yonago deposit is about 7 km long and 30
m wide. Thickness of the deposits is typically 0.2 m. Grade is 57.6% Fe
and 10% TiO2. Ore minerals are magnetite, hematite, and ilmenite. Placer
Fe minerals occur in coastal plane deposits, coastal terrace deposits,
and modern beach sands. Fe minerals in the coastal plane deposits is
major type.</td>
<td>Geological Survey of Japan, 1954; MITI, 1958, 1959; Hasegawa,
1963.</td>
<td>Japan</td>
</tr>
<tr class="even">
<td>J</td>
<td>51</td>
<td>01</td>
<td>39 30 00N</td>
<td>39.5</td>
<td>122 10 00E</td>
<td>122.166666666667</td>
<td>Diamond</td>
<td></td>
<td>Toudaohe area, Fuxian County</td>
<td>Placer diamond</td>
<td>Small</td>
<td>Average grade of 20 to 30 mg/m3 Au, ranges up to 70 mg/m3 Au.</td>
<td></td>
<td></td>
<td></td>
<td>Placer diamond deposits are River valley type and are divided into 4
subtypes. The ore beds consist of of yellow-brown mild clay and/or sand
and gravel beds. The total thickness of the ore beds is 5-6 m.
Clay-bearing sand and gravel beds contain more placer diamond, and
consist of gravel-50-80%, quartz sand-20-30% and clay-5-20%. Rounded
quartz and diamonds and has a diameter of about 0.2-20 cm. The ore
bodies average 13.62mg/m3 and have an variation coefficient of 114%.
Placer diamond derived from the diamond-bearing kimberlite pipes.
Diamond is colorless or faint yellow, and 39% contain graphite
inclusions. Diamond grains are usually less than 1 mg, maximum up to
200-300 mg. Alluvial placers are limited. In alluvial placers, diamond
is hosted in gravel-bearing clay, gravel-bearing mild clay, and mild
clay-bearing gravel beds. The thickness of this type of ore beds is 3-4
m. The grade of diamond in this type of ores is 34.04mg/m3, maximum of
100mg/m3. The placer diamond beds at 200 m from the kimberlite pipes are
most valuable.</td>
<td>Deng Chujun and others, 1994a, b.</td>
<td>China</td>
</tr>
<tr class="odd">
<td>J</td>
<td>51</td>
<td>02</td>
<td>37 10 00N</td>
<td>37.1666666666667</td>
<td>121 30 00E</td>
<td>121.5</td>
<td>Au</td>
<td></td>
<td>Jiaodong (East part of Shandong Province)</td>
<td>Placer Au</td>
<td>Moderate to small.</td>
<td></td>
<td>Reserves of 6 tonnes Au.</td>
<td>699-999</td>
<td></td>
<td>Areas consists of low mountains, hills, and planes in that many
short Rivers drain to the sea and form a dendritic water system. More
than 20 placer Au deposits occur and have been mined since ancient
times. The best placer Au deposits are adjacent to primary gold
deposits, including ore than 10 large gold quartz vein deposits. The
placer Au in the area belongs to alluvial-deluvial River valley type.
The proven placer Au reserve is 6 tonnes, but the potential reserve is
greater than 30 tonnes. The Xinanhe Placer Au deposit has ore bodies
that are 30 km long, 40-600 m wide and 5-16 m thick. Gold grains are
fine to moderate. Other heavy minerals are magnetite, garnet, zircon,
ilmenite and tourmaline.</td>
<td>Chen Jiming and others, 1997.</td>
<td>China</td>
</tr>
<tr class="even">
<td>J</td>
<td>52</td>
<td>01</td>
<td>36 58'00 N</td>
<td>36.9666666666667</td>
<td>126 48'00 E</td>
<td>126.8</td>
<td>Au</td>
<td></td>
<td>Hanjin</td>
<td>Placer Au</td>
<td>Small</td>
<td>Average grade of 0.167gms/yd3 Au.</td>
<td>Reserves of 191 kg Au.</td>
<td></td>
<td></td>
<td>Placer district is underlain by mica schist, quartzite, and
limestone that are intruded by biotite granite with some quartz veins.
At high tide, district is covered with sea water. Generally, the deposit
is low-grade placer but locally high-grade. Thickness of alluvial
deposit is very irregular (max. 52 ft, mim 0.5 ft), with average
thickness 15.8f t. The thickness of the pay strata ranges from 0.3 ft to
2.5 ft. In high-grade part, the alluvium formation is the pay strata.
Gold content and the scope of high-grade are as follows: area-553,750
m3, average depth-4.87 ft, volume-874,500 m3, gold grade-0.1671 gms/yd3,
reserves-191kg. Hanjin beach gold placer occurs along the Hanjin
seashore of Asan bay, Songak-myon, Dangjin-gun, and
Chungchong-namdo.</td>
<td>Park and others, 1964.</td>
<td>Korea</td>
</tr>
<tr class="odd">
<td>J</td>
<td>52</td>
<td>02</td>
<td>36 45 30 N</td>
<td>36.7583333333333</td>
<td>127 14 00 E</td>
<td>127.233333333333</td>
<td>Au</td>
<td></td>
<td>Sungnam</td>
<td>Placer Au</td>
<td>Medium</td>
<td>Average grade of 0.077-0.184 g/yd3 Au, 1.067-5.669 g/yd3
fergusonite.</td>
<td>Ore reserves of 3,857kg gold and 76.5 tonnes of fergusonite.</td>
<td></td>
<td></td>
<td>Placer district is underlain by granite-gneiss intruded by two-mica
granite, of probable Precambrian age. Younger diorite, quartz-veins, and
pegmatites, up to one to two meters wide, occur in the area. Granite
gneiss forms small hills 100 m or less high in the immediate area of the
district, and higher hills (up to 400 m) farther south. The granite
forms rolling ground from one to two hundred m high north of the
deposit. The placer district is about 500 m wide, and extends from east
to west for 10 km along the stream. Maximum thickness is 32 ft.(at hole
151) and a minimum of 8 ft. (at holes 201 and 202). Average thickness is
16.7 ft. in the western mine claim, and 23.5ft. in the eastern. Between
6 and 15 feet of clay occurs locally at the northern and southern
margins of the deposit. Sandy clay occurs in the center of the district,
and ranges from 3 to 34 ft thick. Ore minerals are fergusonite (3.5%
U3O8 ; 1.5% ThO2) and gold. Deposit is 12 km southeast of Chonan in
Sungnam and Sushin-myons, Chonan-gun, Chungchong-namdo.</td>
<td>Hwang and Choi, 1961.</td>
<td>Korea</td>
</tr>
<tr class="even">
<td>J</td>
<td>52</td>
<td>03</td>
<td>36 42' 30 N</td>
<td>36.7008333333333</td>
<td>127 03 00 E</td>
<td>127.05</td>
<td>Au</td>
<td></td>
<td>Asan Bay</td>
<td>Placer Au</td>
<td>Medium</td>
<td>Average grade of 0.190 to 0.253 g/yd3 Au.</td>
<td>Reserves of 1,748 kg Au.</td>
<td></td>
<td></td>
<td>Upper course in district contain minable gold placers with many
nearby lode gold mines. Two wide alluvial basins contain mostly clay,
and are very wide. Average thickness of alluvium is about 9.8 m with a
sequence of surface clay 7 m, clay and sand from 7 to 8 m, sand from 8
to 9 m, and sand and pebble from 9 to 10 m. Bedrock is augen gneiss in
Pyongtaik area and granite gneiss in Yesan area.</td>
<td>Lee and Yoon, 1970.</td>
<td>Korea</td>
</tr>
<tr class="odd">
<td>J</td>
<td>52</td>
<td>04</td>
<td>36 38'00N</td>
<td>36.6333333333333</td>
<td>126 42'30E</td>
<td>126.708333333333</td>
<td>Au</td>
<td></td>
<td>Kumma-chon</td>
<td>Placer Au</td>
<td>Medium</td>
<td>Grade range of 0.05-0.27 g/yd3 Au.</td>
<td>Reserves of 1,236 kg ore.</td>
<td></td>
<td></td>
<td>Consists of ilmenite and gold placers that are underlain by
coarse-grained granite gneiss of probable Precambrian age. Younger
quartz veins and pegmatites 0.8 to 2.5 meters wide occur in this area.
The granite gneiss forms small hills 120 meters or less in height in the
immediate area of the deposit and higher hills farther southeast. The
granite forms rolling ground from 80 to 200 meters high west of the
deposit. The placer is about 800 m wide and extends from south to north
6.5 km along the stream. The maximum thickness of the alluvium are
26.4ft and minimum thickness is 12 ft. The average thickness is 18.99 ft
(5.79m) in the southern area and 19.23 ft (5.86m) in the northern area.
The alluvium formation includes clay between 4 and 10 ft locally at the
margins of the deposit. Sandy clay in the center of the placer ranges
from 5 to 15 ft thick. The alluvial placer is 3.5 km northwest
Kumma-myon, Hongsoung-gun and Sapkyo-myon, Yaesan-gun, and
Chunchong-namdo.</td>
<td>C. I. Choi and K. B. Kim, written commun., 1963.</td>
<td>Korea</td>
</tr>
<tr class="even">
<td>J</td>
<td>52</td>
<td>05</td>
<td>36 32 30 N</td>
<td>36.5416666666667</td>
<td>127 27 50 E</td>
<td>127.463888888889</td>
<td>Au</td>
<td></td>
<td>Musim-chon</td>
<td>Placer Au</td>
<td>Small</td>
<td>Average grade of 0.260g/yd3. Au.</td>
<td>Total reserves of 1,992 kg Au</td>
<td></td>
<td></td>
<td>District about 100m wide and extendd south to north for 11.5 km
along the stream. Average thickness of alluvium is about 15.4 ft (4.8m).
The deposit overlies Precambrian schist that is intruded by
coarse-grained Jurassic biotite granite and lamprophyre. The alluvium
formation is mostly coarse sand, and contains more conglomerate in upper
part of the stream than lower part. Total area is 1,238km2; volume is
7,785,250 yd3 (5,943,000m3). Placer occurs in the western part of
Chongju city, Chungchong-pukdo.</td>
<td>J. K. Lee and B. C. Kim, written commun., 1969.</td>
<td>Korea</td>
</tr>
<tr class="odd">
<td>J</td>
<td>52</td>
<td>06</td>
<td>38 17'30N</td>
<td>38.2916666666667</td>
<td>128 33'30E</td>
<td>128.558333333333</td>
<td>Th</td>
<td>REE</td>
<td>Kosong</td>
<td>Placer Th</td>
<td>Medium</td>
<td>Average grade of 2,586 g/m3 monazite and 44,100 g/m3 ilmenite.</td>
<td>Reserves of 56,654 tonnes ore.</td>
<td></td>
<td></td>
<td>Consists of ilmenite, monazite and zircon bearing placers that occur
along the shore ine in Hyonnae-myon, Kojin-myon and Kansung-myon of
Kosong-gun, and Chuckwang-myon of Yangyang-gun, Kangwon-do areas.
Country rock is mostly Precambrian mica schist and injection gneiss,
with younger granite. Heavy mineral sands were concentrated on the beach
by wave action, and the grades of the component minerals of heavy sand
are high enough for economic exploration. Grade averages 2,586 gms
monazite, 9800 gms zircon, 4,119 gms magnetite, 36,400 gms garnet and
44,100 gms ilmenite per cubic meter of sand.</td>
<td>S. K. Yoon, I. C. Hwang and Y. H. Chang, written commun., 1959.</td>
<td>Korea</td>
</tr>
<tr class="even">
<td>J</td>
<td>54</td>
<td>01</td>
<td>38 32 50N</td>
<td>38.5472222222222</td>
<td>141 09 11E</td>
<td>141.153055555556</td>
<td>Au</td>
<td></td>
<td>Kitakami</td>
<td>Placer and paleoplacer Au</td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td>Nishimikawa district contains historical placer deposits. Gold was
discovered in 749 from this district. First placer deposit located at
Koganehazama in Wakuya town, Miyagi Prefecture. Deposits were exhausted
in historical time, and not much detailed information is available. Area
consists of sandstone of Miocene Koganehazama Formation that may also
may contain paleoplacer Au deposits. Alluvial placer deposits also
occur. District covers most of southern Kitakami Mountains and western
foothill of the mountains. Size of district is 60 km by 40 km, elongated
NS. A large number of lode gold deposits occur in the district, and are
probable source of the placer gold.</td>
<td>Watanabe, 1939; Watanabe, 1950; Oide and others, 1989.</td>
<td>Japan</td>
</tr>
<tr class="odd">
<td>J</td>
<td>54</td>
<td>02</td>
<td>37 54 21N</td>
<td>37.9058333333333</td>
<td>138 19 47E</td>
<td>138.329722222222</td>
<td>Au</td>
<td></td>
<td>Nishimikawa</td>
<td>Placer and paleoplacer Au</td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td>Nishimikawa district contains at least 32 alluvial placer deposits.
Gold occurs as paleoplacer deposits and placer deposits. 16 paleoplacer
deposits occur around Sasagawa village, and are hosted in sand and
conglomerate of the lower to middle Miocene Orito Formation. Gold is
concentrated in lower 23 m of a 70-m-thick conglomerate formation.
Paleoplacer deposits contain average of 0.23 g/t of gold. Placer
deposits occur in the lower reaches of Nishimikawa Rver flowing from the
Sasagawa village area. The deposits occur in alluvial deposits and
alluvial terrace deposits. The size of the district is 6 km by 5 km.
Mining started at least in 1100, and likely from 1022. Several tonnes
(at least 1.5 tonnes) of gold were produced form the district. Mining
stopped in 1872.</td>
<td>Kosuge, 1988; Mining and Materials Processing Institute of Japan,
1994.</td>
<td>Japan</td>
</tr>
<tr class="even">
<td>K</td>
<td>48</td>
<td>01</td>
<td>42 01 20N</td>
<td>42.0222222222222</td>
<td>104 54 00E</td>
<td>104.9</td>
<td>SnO2</td>
<td>(Mn,Fe)WO4</td>
<td>Khar Morit</td>
<td>Placer Sn</td>
<td></td>
<td>Average grade of 500 g/m3 SnO2.</td>
<td>Reserves of 7,090 tonnes SnO2.</td>
<td></td>
<td></td>
<td>More than 10 valleys with placer deposits occur around Khar Morit
Mountain in a region of moderate relief. Most placers are near-surface
alluvial deposits in first-order stream valleys, forming single Holocene
stratum concentrations. Multiple pay layers are rare. The cassiterite
placers extend for a length of 4 km. The thick ranges from 0.5 m, and
average concentration of cassiterite is 200-600 g/m3 with locally up to
1000 g/m3 cassiterite. Eluvial-talus placer deposits occur near the top
of mountan where lode deposits occur. Placers are mainly monomineralic,
but small admixtures of wolframite (from 10 to 30% of cassiterite), and
scheelite occur. Cassiterite-silicate stockwork, streaky zones,
mineralized greisens, and rare veins are the main lode sources.
Cassiterite grains are coarse (80% of grain size larger than 5-8 mm).
The content of Sn in lode deposits ranges from 0.5 to 1.0%.</td>
<td>E. Iotov and others., written commun., 1972; N.A. Marinov, written
commun., 1977.</td>
<td>Mongolia</td>
</tr>
<tr class="odd">
<td>K</td>
<td>49</td>
<td>01</td>
<td>41 30 00N</td>
<td>41.5</td>
<td>110 30 00E</td>
<td>110.5</td>
<td>Au</td>
<td></td>
<td>Yinshan, Inner Mongolia</td>
<td>Placer Au</td>
<td>Small</td>
<td></td>
<td></td>
<td></td>
<td></td>
<td>Occurs in Yinshan Mountains and the drainages of the branches of the
Yellow River. Many placer Au deposits in the area are alluvial,
alluvial-deluvial River channel, and River flat types. Scale is usually
small. Together with the placer Au in the Yanshan area in K-50-01,
totally gold reserves is up to 30 tonnes. Gold derived from the primary
gold deposits and quartz veins in Archean metamorphic rock of the Jining
Group, and from Mesozoic syenite and granite. In the area, a series of
primary gold deposits occur and are mined. Jinpen placer Au deposit in
the area is eluvial- drift bed type, is 1300-7293 m long, 23-24 m wide,
averages 1.0m thick, and contains 1.4g/ m3. Gold grains greater than 5mm
comprise 17%, 5-1mm-48%, and 1-0.4 mm-27%. Gold nuggets occur. Gold
derived from the Au lodes in upper stream areas.</td>
<td>Chen Jiming and others, 1997.</td>
<td>China</td>
</tr>
<tr class="even">
<td>K</td>
<td>49</td>
<td>02</td>
<td>40 09 40N</td>
<td>40.1611111111111</td>
<td>141 42 56E</td>
<td>141.715555555556</td>
<td>Fe</td>
<td>Ti</td>
<td>Kuji</td>
<td>Placer Fe</td>
<td></td>
<td>Average grade of 23.0% Fe and 5.8% TiO2.</td>
<td></td>
<td></td>
<td></td>
<td>Consists of Pleistocene placer and paleo-placer deposits. Main part
of the district is about 16 km long and 4 km wide, and is in western
part of Kuji city, Iwate Prefecture. The Pleistocene Formation consists
of sandstone, is about 30 m thick, and forms a 200-300 m high terrace.
Thickness of placer deposits is 2 to 4 m. Average grade is about 22.5%
Fe and about 7% TiO2. Sands include magnetite, hematite, ilmenite,
limonite, pyroxene, hornblende, quartz, and plagioclase. Historical
records indicate extensive mining operation between 1660 and 1760.
Japanese traditional Nambu Ironware used iron from this deposits.</td>
<td>Geological Survey of Japan, 1954; MITI, 1959, 1959; Hasegawa,
1963.</td>
<td>Japan</td>
</tr>
<tr class="odd">
<td>K</td>
<td>50</td>
<td>01</td>
<td>41 10 00N</td>
<td>41.1666666666667</td>
<td>118 30 00E</td>
<td>118.5</td>
<td>Pt</td>
<td></td>
<td>Gaositai</td>
<td>Placer PGE</td>
<td>Small</td>
<td></td>
<td></td>
<td></td>
<td></td>
<td>District located in the Damiao V-Ti-Fe-bearing mafic-ultramafic rock
belt in Hebei Province. Placer Pt occurs in Quaternary River channel and
placer terrain deposits. Conglomerate beds of the terrain deposits
consist of Ti-magnetite, galena, chromite, and mafic-ultramafic rock
debris. Placer Pt accompanied by placer gold and is concentrated at the
base of the conglomerate. In the concave sites of the weathered surface
of the basement rock, placer Pt and Au are enriched. 80% of placer Pt
minerals are the alloys of Pt, Ir and Os, and 20% are PGE.</td>
<td>Xu Enrong and others, 1994.</td>
<td>China</td>
</tr>
<tr class="even">
<td>K</td>
<td>50</td>
<td>02</td>
<td>40 30 00N</td>
<td>40.5</td>
<td>119 30 00E</td>
<td>119.5</td>
<td>Au</td>
<td></td>
<td>Yanliao</td>
<td>Placer Au</td>
<td>Small</td>
<td></td>
<td></td>
<td></td>
<td></td>
<td>Occurs in mild to low hills of the Yanshan Mountains. The main River
systems are the Laohahe, Dalinghe, Luanhe, and Shangganhe Rivers. Placer
Au deposits are widely distributed in the area, and are deluvial,
alluvial-deluvial River channel, River flat, and first order terrain
types. All are small. Gold derived mainly from the gold-bearing quartz
veins in Archean metamorphic rock of the Jianping and Jianxi Groups and
from various Mesozoic granites. Total of 30 tonnes gold has been proven
combined with the placer Au deposits in Yinshan area in K-49-01.</td>
<td>Chen Jiming and others, 1997.</td>
<td>China</td>
</tr>
<tr class="odd">
<td>K</td>
<td>51</td>
<td>01</td>
<td>40 54 08N</td>
<td>40.9022222222222</td>
<td>141 23 08E</td>
<td>141.385555555556</td>
<td>Fe</td>
<td>Ti</td>
<td>Kamikita</td>
<td>Placer Fe</td>
<td></td>
<td>Average grade of 17.3% Fe and 3.0% TiO2.</td>
<td></td>
<td></td>
<td></td>
<td>Consists of a large number of placer deposits in eastern Aomori
along the Pacific Ocean. Main part of the district is about 40 km long
and 0.5 to 1 km wide, and occurs between Sabishiro and Tomari. Placer Fe
had been mined in five locations in the district. Sabishiro and Misawa
mines are in the district. Placer Fe minerals occur in the coastal plane
deposits, coastal terrace deposits, and modern beach sands. Thickness of
deposits is about 1.5-2 m, and consists of a large number of
magnetite-rich horizons that range up to 5 cm thick. Average grade is
about 17.3% Fe and 3.0% TiO2. Sands include magnetite, hematite,
ilmenite, limonite, pyroxene, hornblende, quartz, and plagioclase.</td>
<td>Geological Survey of Japan, 1954.</td>
<td>Japan</td>
</tr>
<tr class="even">
<td>K</td>
<td>51</td>
<td>02</td>
<td>40 30 00N</td>
<td>40.5</td>
<td>123 25 00E</td>
<td>123.416666666667</td>
<td>Au</td>
<td></td>
<td>Liaodong (Eastern Liaoning Province)</td>
<td>Placer Au</td>
<td>Small</td>
<td></td>
<td></td>
<td>590-877</td>
<td></td>
<td>Deposits are scarcely distributed in the tributaries of the Liaohe,
Taizhihe, and Yalujiang Rivers. The Zhongtanghe area along the Zhongtang
River, that belongs to the second tributary of the Taizhi River,
contains several small-moderate Quaternary alluvial placer Au deposits.
Au mainly derived from the base metal sulphide veins and gold quartz
veins in metamorphic rock of the Early Proterozoic Liaohe Group. The
Zhongtang River placer Au body is 6.0 km long, 50-250 m wide, and occurs
along the valley of the Zhongtang River along a NNE direction. Au grains
are 0.3-1.0 mm in diameter.</td>
<td>Feng Xishan, 1991.</td>
<td>China</td>
</tr>
<tr class="odd">
<td>K</td>
<td>52</td>
<td>01</td>
<td>43 15 00N</td>
<td>43.25</td>
<td>130 17 00E</td>
<td>130.283333333333</td>
<td>Au</td>
<td></td>
<td>Hunchun-Huadian, Jilin Province</td>
<td>Placer Au and paleoplacer Au</td>
<td>Small</td>
<td></td>
<td></td>
<td>843-872</td>
<td></td>
<td>Occurs in Changbaishan Mountains in eastern Jilin province with
three large water systems-Yalujiang, Tumenjiang, and Songhuajiang
Rivers. In 2nd to 4th order subbranches, placer Au deposits are
widespread and have been mined for a long time. These include the
Hunchun, Hunjiang, and Jiapigou areas, where some large primary gold
deposits occur. At the Hunchun area, mining started 1000 years ago. The
area occurs in Hunchun near the border between Russia and China, and
belongs to drainage of the Tumen River, a first order of tributary of
the upper Hunchun River. The placers are alluvial valley channel and
valley terrace types. Au derived from gold lodes (Xiaoxinancha gold
deposit), base metal veins and Tertiary paleo-placers in basal
conglomerate (Chunhua deposit). The Hunchun River Placer Au is
relatively large, and gold is coase-grained and platy, and generally
averages 1.0 mm, locally up to 2 mm in diameter. The Hunchun-Huadian
district also contains a group of Miocene paleoplacer Au deposit in the
Huangsongdingzi area. The paleoplacer deposits occur in basal
conglomerate of the Tertiary Tuchengzhi Formation. Two placer Au
horizons are identified. One horizon is 2,600 m long, 1,000 m wide, and
1.87 m thick. The horizons vary from massive to bedded. More than 30
heavy minerals occur in the horizons. Besides gold, common heavy
minerals are ilmenite, pyrite, magnetite, arsenopyrite, and limonite.
Other minerals include feldspar, quartz, amphibole, sericite, biotite,
chlorite, garnet, andalusite, pyroxene, spinel, sillimanite, zircon,
sphene, apatite, rutile, corundum, and others. The source for the
horizons are intermediate to siliceous intrusive rock and associated
hydrothermal gold veins.</td>
<td>Liu Baocheng and Yuan Li, 1994; Chen Jiming and others, 1997.</td>
<td>China</td>
</tr>
<tr class="even">
<td>K</td>
<td>54</td>
<td>01</td>
<td>43 54 45N</td>
<td>43.9125</td>
<td>142 05 58E</td>
<td>142.099444444444</td>
<td>Pt, Cr, Au</td>
<td></td>
<td>Horokanai</td>
<td>Placer PGE</td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td>District consists of alluvial PGE and Au placer deposits. The size
of the district is 45 km by 30 km, elongated to NS. The deposits are
underlain mainly by serpentinite of Kamuikotan belt. The placer deposits
occur in Uryu River and Inushibetu River, a tributary of Teshio River.
Main deposits in the district are at Takadomari and Horokanai. Heavy
metals of deposits contain 20-30% of Au. Average grade is 0.4g/m2. The
grade increase to 4 g/m2 ilocally. Ore minerals are rutheniridosmine,
osmium, and ruthenium.</td>
<td>Geological Survey of Japan, 1955; Saito and others, 1967.</td>
<td>Japan</td>
</tr>
<tr class="odd">
<td>K</td>
<td>54</td>
<td>02</td>
<td>43 02 35N</td>
<td>43.0430555555556</td>
<td>142 09 38E</td>
<td>142.160555555556</td>
<td>Pt, Au</td>
<td></td>
<td>Shirokingawa</td>
<td>Placer PGE</td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td>District contains alluvial PGE and Au placer deposits. Size of the
district is 70 km by 40 km, elongated to NS. The deposits are underlain
mainly by serpentinite of Kamuikotan belt. The placer deposits occur in
Shirokingawa, a tributary of Yubari, Sorachigawa, Mukawa, and Niseu
Rivers, a tributary of Sarugawa River. Main deposits in the district are
at Shirokinzawa and Numanosawa. The Shirokinzawa deposit occurs for 12
km along the River. PGE minerals occurr in terrace deposits around the
River. The grade ranges up to 0.1 g/m2. Ore minerals are mostly
Os-minerals. Heavy metals in deposits also contain 20-30% of Au.</td>
<td>Suzuki, 1950; Geological Survey of Japan, 1955; Saito and others,
1967; Nakagawa, 1994.</td>
<td>Japan</td>
</tr>
<tr class="even">
<td>K</td>
<td>54</td>
<td>03</td>
<td>42 33 21N</td>
<td>42.5558333333333</td>
<td>140 09 43E</td>
<td>140.161944444444</td>
<td>Au</td>
<td></td>
<td>Imagane</td>
<td>Placer and paleoplacer Au</td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td>District contains alluvial placer deposits. Dstrict is 25 km by 20
km. Deposits occur along Toshibetu River. Two main deposits occur at
Meppugawa and Toshibetugawa. Placer gold occurs in alluvial deposits in
the River. The deposits are underlain by Paleozoic to Mesozoic
sedimentary and granitic rock. Placer gold has been mined since 1804 at
the Toshibetsugawa deposit. This deposit produced 12 kg of gold from
1934 to 1943.</td>
<td>Saito and others, 1967; Kato and others, 1990.</td>
<td>Japan</td>
</tr>
<tr class="odd">
<td>K</td>
<td>54</td>
<td>04</td>
<td>42 26 55N</td>
<td>42.4486111111111</td>
<td>140 19 43E</td>
<td>140.328611111111</td>
<td>Fe</td>
<td>Ti</td>
<td>Funkawan</td>
<td>Placer Fe</td>
<td></td>
<td>Average grade of 24% Fe and 3.2% TiO2.</td>
<td></td>
<td></td>
<td></td>
<td>Consists of a large number of beach placer deposits. Main part of
the district is about 18 km long and 0.5 to 1 km wide, and occurs
between Oshamanbe and Kuroiwa. More than 20 deposits have been mined.
Major deposits are at Kunnui, Oshamanbe, Nakanosawa, Hanaoka, Toyono,
and Toyotu. Placer Fe minerals occur in coastal plane deposits, coastal
terrace deposits, and modern beach sands. Fe minerals in the coastal
plane deposits is major type. Most of deposits occur from several
hundreds m to 600 m above present shore line. Thickness of deposits
ranges from 5 to 1m. Average grade is about 15-30% Fe and 4% TiO2, with
maximum grade of 60% Fe and 6.5% TiO2. Sands include magnetite,
hematite, ilmenite, limonite, pyroxene, chlorite, quartz, and
plagioclase.</td>
<td>Geological Survey of Japan, 1954; Saito, 1967.</td>
<td>Japan</td>
</tr>
<tr class="even">
<td>K</td>
<td>54</td>
<td>05</td>
<td>41 33 34N</td>
<td>41.5594444444444</td>
<td>140 12 45E</td>
<td>140.2125</td>
<td>Au</td>
<td></td>
<td>Matsumae</td>
<td>Placer and paleoplacer Au</td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td>District consists of alluvial placer deposits. District is 25 km by
25 km. Placer deposits occur in Rivers around Daisengendake Mountain.
The main deposits occur along Shiriushi River. Placer gold occurs in
alluvial deposits in river and alluvial terrace deposits. Deposits are
underlain by Paleozoic and Mesozoic sedimentary rock. Quartz veins in
sedimentary rock are likely the source of placer gold.</td>
<td>Saito and others, 1967; Kato and others, 1990.</td>
<td>Japan</td>
</tr>
<tr class="odd">
<td>L</td>
<td>45</td>
<td>01</td>
<td>47 30 00N</td>
<td>47.5</td>
<td>89 20 00E</td>
<td>89</td>
<td>Au</td>
<td></td>
<td>Altai, Xinjiang</td>
<td>Placer Au</td>
<td>Moderate</td>
<td></td>
<td>10 tonnes of gold produced in 1951-1942, and 33.9 tonnes of gold
produced since 1980. Predicted gold reserves are greater than 30
tonnes.</td>
<td>997</td>
<td></td>
<td>Six mines are in operation. First order drainage systems are the EW
Erqisi and Wuluohe Rivers. Third to fifth order branches usually have
placer gold. Moraine placer Au deposits are several tens of km long, 40
to 120 m wide, and 3 to 15m thick. Grade ranges from 0.38 g/m3 to 2.2
g/t. Glaciofluvial and alluvial-deluvial River valley placer deposits
range up to several tens of km long, 5 to 20m wide, and range from
0.15-0.25 to 23.5 g/m3. Alluvial-deluvial River flat deposits range up
to several tens of km long, 100-500 m wide, 5 to 10 m thick, and range
from 0.1-0.15 to 3.5 g/m3. Gold is derived from quartz veins in
Hercynian granite and from metamorphosed Ordovician through
Carboniferous strata. The typical Xichahe placer Au deposit is moderate
size and is a glaciofluvial River valley type. The ore bodies are
usually 3 to 4 km long, 80 m wide, 6 to 10 m thick, and with an average
grade of 0.37 g/m3. Diameter of gold grains is 0.3-1.0 mm with a maximum
of 2.48 mm. Heavy minerals in the ores include zircon, magnetite,
garnet, pyrite, and cinnabar. 10 tonnes of gold produced in 1951-1942,
and 33.9 tonnes of gold produced since 1980.</td>
<td>Lu Yingjie and others, 1992; Chen Jiming and Others, 1997.</td>
<td>China</td>
</tr>
<tr class="even">
<td>L</td>
<td>47</td>
<td>01</td>
<td>46 25 00N</td>
<td>46.4166666666667</td>
<td>100 07 00E</td>
<td>100.116666666667</td>
<td>Au</td>
<td></td>
<td>Dovont</td>
<td>Placer Au</td>
<td></td>
<td>Average grade of 580 mg/m3 to 1015 mg/m3 Au.</td>
<td>Production: 0.02 tonnes Au in 1992, 0.117 tonnes in 1993, 0.131
tonnes in 1994, and 0.147 tonnes in 1995. Proven reserves of 6.2 tonnes
Au.</td>
<td>887 - 943</td>
<td></td>
<td>Occurs in the middle part of the Bayankhongor metallogenic belt, in
the Dovont Mountains. Most placer Au deposits are alluvial-proluvial
type, and minor alluvial type. There also are several manmade placers.
Alluvial deposits are older than the alluvial-proluvial type. Main
placer Au deposits are the Sairan-hudag, Mukkharereg, Ovorchuluut,
Jargalant, Archuluut, Khooloi-khudag, and Dalt.Most deposits were partly
mined out in 1939-1953. Presently, deposits and other small placer Au
deposits of the Bayankhongor belt are being mined intensively. Deposits
vary from 0.4 km to 6.6 km long, 30 m to 220 m wide, and from 0.6-1.8 m
thick. Proven reserves range from 0.082 to 1.55 tonnes Au. Some
deposits, for-example the Archuluut and the Buht located in NE foothills
of the Dovont Mountains, occur in approximately 100-m-thick sediments,
and have Au-rich several stratas from 8.5 m to 48.5 m depth. The
Archuluut deposit was partly mined in 1939-1953 with production of 680
kg Au. Placer Au deposits in SW slope of the mountain range are covered
with up to 3.2 m of barren sediments. Some placers, for-example, the
Sairan-khudag alluvial deposit, has two Au-rich strata. Primary source
of gold is not known. Bedrock consists mostly of late Riphean to Early
Cambrian greenschist and a Vendian to Early Cambrian ophiolite
complex.</td>
<td>D. Andreas and others, written commun., 1970; Mormily and Tegshil,
1971; Blagonravov and Shavolovskyi, 1977; B. Bat-Oroom and others,
written commun., 1980.</td>
<td>Mongolia</td>
</tr>
<tr class="odd">
<td>L</td>
<td>48</td>
<td>01</td>
<td>46 27 05N</td>
<td>46.4513888888889</td>
<td>102 22 05E</td>
<td>102.368055555556</td>
<td>Au</td>
<td></td>
<td>Uyanga-Taragt</td>
<td>Placer Au</td>
<td></td>
<td>Average grade of 845 to 1100mg/m3 Au.</td>
<td>Production of 0.6 tonnes Au in 1993-1995. Reserves of 4.5 tonnes
Au.</td>
<td>840 - 860 (average 853 )</td>
<td></td>
<td><p>Occurs in the middle part of the East-Khangai metallogenic belt
in northern valleys of the upper part of the Ongiin-gol River. District
strikes NW-SE, is approximately 40 km long, and 30 km wide. Bedrock is
mainly Early to Middle Devonian volcanic, sedimentary, and siliceous
rock in the Erdenetsogt Formation that is intruded by Late Permian
granodiorite to granite small stocks of the Khangai Complex.</p>
<p>District divided into the Uyanga, the Taragt, and Zuunbayan-Ulaan
subdistricts. Placer Au is derived from nearby quartz vein and
replacement Au and probably from Early to Middle Jurassic conglomerate.
Known placer deposits and prospects occur mainly in N-S striking
valleys. Known placers belong to alluvial and alluvial-proluvial types.
Valleys of main rivers are well developed, and have few terraces.</p>
<p>The Uyanga subdistrict occurs in the NW part of the district,
approximately 5 km in north of the Uyanga village. Main placer Au
deposits occur in the Olt River valley and tributaries. Estimated
reserve is approximately 3.0 tonnes Au. The largest placer deposit is
the Olt placer that is 3.5 km long, averages 187 m wide, and ranges from
0.6 m to 3.6 m thick (average 1.44 m). The Au rich strata are covered by
from 0.8 m to 2.4 m thick, barren sediments. The proven reserve is 0.85
tonnes Au at average grade 872 mg/m3 (from 167 mg/m3 to 2747 mg/m3).
Most Au grains are from 3.0 to 40.0 mm Placer Au deposits in the
subdistrict were mined out from 1994 by the private Erel Mongolian
company.</p>
<p>The Taragt subdistrict occurs in southern part of the district,
occurs approximately 3-5 km north to northeast of the Taragt village.
Placer Au deposits, as at Khuree-sair, Sort-am and Olziim-bulag occur in
proluvial-alluvial valleys that drain from Early to Middle Jurassic
conglomerate. Placers of the subdistrict have been known since 1940. The
Zuunbayan-Ulaan sundistrict occurs in northern part of the district,
approximately 10 km NW of the Zuunbayan-Ulaan village. Known small
(0.1-0.2 tonnes Au) placer Au deposits and prospects occur in
proluvial-alluvial valleys draining Early to Middle Devonian volcanic
and sedimentary rock. Placer Au deposits and prospects of the
subdistrict were discovered in 1995.</p></td>
<td>D. Urtnasan and others, written commun., 1970; Blagonravov and
Shavolovskyi, 1977; Ch. Baadai and others, written commun., 1992.</td>
<td>Mongolia</td>
</tr>
<tr class="even">
<td>L</td>
<td>48</td>
<td>02</td>
<td>47 07 05N</td>
<td>47.1180555555556</td>
<td>107 17 05E</td>
<td>107.284722222222</td>
<td>Au</td>
<td></td>
<td>Baruun -Urt</td>
<td>Placer Au</td>
<td></td>
<td>Average grade of 1.0 g/m3 Au.</td>
<td>Production of 0.5 tonnes in 1994 and 1995. Reserves of 1.5 tonnes
Au.</td>
<td></td>
<td></td>
<td>Occurs in SW part of the South Khentii metallogenic belt, strikes
NE, and is along the North Govi fault zone. District is approximately 50
km long and 30 km wide. Bedrock is mainly early Paleozoic clastic rock
intruded by small early Mesozoic granotoids. Primary source of placer Au
not defined. Placer Au deposits are small and proluvial-alluvial type.
Main deposits are at Baruun-Uurt, Western Baruun-Urt, Khushuu-Uul, and
Salkhitai. Largest is the Baruun-Urt deposit that is 7 km long, 40 to
400 m wide, and approximately 1 m thick. Grade of Au ranges from a few
grains to 49,20 mg/m3. Deposit was mined out in 1994.</td>
<td>Sanjsugar, written commun., 1988.</td>
<td>Mongolia</td>
</tr>
<tr class="odd">
<td>L</td>
<td>48</td>
<td>03</td>
<td>47 42 30N</td>
<td>47.7083333333333</td>
<td>107 35 00E</td>
<td>107.583333333333</td>
<td>SnO2</td>
<td>(Mn,Fe)WO4</td>
<td>Janchivlan</td>
<td>Placer Sn</td>
<td></td>
<td>Averade grade of 500g/m3 SnO2.</td>
<td>Reserves of 7,090 tonnes SnO2.</td>
<td></td>
<td></td>
<td>More than ten Sn placer deposits, such as the Janchivlan, Baatar,
Bayandavaa, Elstei, Zuun Elstei, and Avdrant deposits, occur in the
Janchivlan district. The placer deposits occur in first-to third-order
stream valleys. Pay zones of late Pleistocene to Holocene placers range
up to 7 km long and are generally simple single-layered deposits. These
placers occur in gravel deposits. Heavy minerals are cassiterite,
scheelite, wolframite, monozite, berill, ilmenite, fluorspar,
molybdenite, gold, magnetite, and pyrite. All the deposits and small
eluvial-talus placers are associated with quartz-cassiterite veins and
greisens of the Janchivlan, Urt Gozgor, and other lode deposits. Lode
deposits contain cassiterite and quartz.</td>
<td>M.G. Korolev and others, written commun., 1955; G.Y. Borodyev and
others., written commun., 1960; E.N. Chetverikov and others, written
commun., 1975; Bykovsky and others, 1977a, b; B. Baasan, written
commun., 1988.</td>
<td>Mongolia</td>
</tr>
<tr class="even">
<td>L</td>
<td>48</td>
<td>04</td>
<td>46 15 00N</td>
<td>46.25</td>
<td>106 01 30E</td>
<td>106.025</td>
<td>SnO2</td>
<td></td>
<td>Baga Gazar</td>
<td>Placer Sn</td>
<td></td>
<td>Averade grade of 500 g/m3 SnO2.</td>
<td>Reserves of 7,090 tonnes SnO2.</td>
<td></td>
<td></td>
<td>District contains at least three placer deposits. Main resources
occur in valley bottoms of first-to second-order streams, mainly in
Recent alluvial material. Thickness of ore stratum ranges from 2.5 to
6.5 m. Width of alluvial placers ranges up to 130 m. Pay zones of
placers range up to 5 km long and are generally simple single-layered
deposits. Most cassiterite grains average less than 7 mm diameter.
Tuviin deposit is richest and contains up to 370 g/m3 tin. Main placer
minerals are quartz, topaz, cassiterite, and biotite. Topaz-cassiterite
greisen (zivettery) is the main lode sources of metals. Zivettery occurs
mainly along inside boundaries of silicate masses with coarse-grain
topaz.</td>
<td>G.Y. Borodyev and others, written commun., 1962; N.M. Zasimovskii
and others, written commun., 1955; B. Baasan, written commun., 1969; N.
Buyan., written commun., 1969; Khasin and Zakhai., 1977.</td>
<td>Mongolia</td>
</tr>
<tr class="odd">
<td>L</td>
<td>49</td>
<td>01</td>
<td>47 46 30N</td>
<td>47.775</td>
<td>109 07 45E</td>
<td>109.129166666667</td>
<td>SnO2</td>
<td>(Mn,Fe)WO4</td>
<td>Modot</td>
<td>Placer Sn</td>
<td></td>
<td>Reserves of 7,012 tonnes SnO2. Averade grade of 320g/m3 SnO2.</td>
<td></td>
<td></td>
<td></td>
<td>Placer tin mined from modern streams and benches. Khyjikhan area and
Bayan Mod basin are most productive. Heavy minerals include cassiterite,
wolframite, fluorspar, molybdenite, gold, magnetite, scheelite, and
pyrite. Placers range from 5-7 km long and are generally simple
single-layered deposits. Placer deposits at Khujikhan contain maximum up
to 1000g/m3 tin, locally more (4500g/m3 tin; 1500 g/m3 wolframite). Tin
probably derived from quartz-cassiterite-wolframite vein and greisen
lode deposits in contact zones in Neoproterozoic schist that is intruded
by Mesozoic hypabyssal granitic plutons. Local bedrock is metamorphosed
Neoproterozoic sedimentary and volcanic rock, and late Mesozoic granitic
plutons.</td>
<td>Bykovsky and others, 1977a, b; L.E. Esipov and others, written
commun., 1978; E. Jadambaa and others, written commun., 1989; D. Erdene,
written commun., 1990.</td>
<td>Mongolia</td>
</tr>
<tr class="even">
<td>L</td>
<td>52</td>
<td>01</td>
<td>47 10 00N</td>
<td>47.1666666666667</td>
<td>130 30 00E</td>
<td>130.5</td>
<td>Au</td>
<td></td>
<td>Jiayin</td>
<td>Placer Au</td>
<td>Large</td>
<td></td>
<td>Production of 80 tonnes Au from 1920-1995.</td>
<td>877</td>
<td></td>
<td>The placer district covers 26,000 sq.km. and belongs to the systems
of Heilongjiang River (including tributaries of Sunhe and Jiayin
Rivers), and the Songhuajiang River (including tributaries of Dulu,
Wutong, and Tangwang Rivers). Placer Au deposits are mainly alluvial
valley type, and partly alluvial valley terrace type. Au mainly derived
from gold lodes in metamorphic rock and granite (including the large
Tuanjiegou gold deposit). The Jiulizhuangh River placer Au deposit is
representative of the placer Au deposits in the area. The ore bodies
occur along the river valley in single layers and in lenses. Au is
tabular and layered. Associated minerals are magnetite, pyrite, garnet,
and tourmaline.</td>
<td>Lu Yingjie and others, 1988; Chen Jiming and others, 1977.</td>
<td>China</td>
</tr>
<tr class="odd">
<td>L</td>
<td>52</td>
<td>02</td>
<td>46 20 00N</td>
<td>46.3333333333333</td>
<td>130 55 00E</td>
<td>130.916666666667</td>
<td>Au</td>
<td></td>
<td>Huanan</td>
<td>Placer Au</td>
<td>Large</td>
<td></td>
<td>Reserves of up to 80 tonnes Au.</td>
<td>820</td>
<td></td>
<td>District covers 28,000 km2 and belongs to the drainage area of
Mudanjiang and Weikenhe Rivers and their tributaries (these rivers are
also the tributaries of the Songhuajiang River), and to the drainage
area of Mulinghe River and related branches of the Wusulijiang River.
Placers are mainly are alluvial, slope wash-proluvial valley flat, and
valley channel deposits. Au mainly derived from gold quartz veins in
Paleoproterozoic metamorphic rock and the Jurassic and Tertiary
gold-bearing conglomerate. Typical placer Au is the Shitouhezhi placer
Au deposit, that contains ore in beds or in lenses along the rivers in
alluvial and alluvial-proluvial sediments, basal conglomerate beds, and
in residual rock debris. The grain size of gold is 0.2-0.4mm.</td>
<td>Lu Yingjie and others, 1988; Chen Jiming and others, 1997.</td>
<td>China</td>
</tr>
<tr class="even">
<td>L</td>
<td>52</td>
<td>03</td>
<td>44 30 00N</td>
<td>44.5</td>
<td>131 00 00E</td>
<td>131</td>
<td>Au</td>
<td></td>
<td>Dongning</td>
<td>Placer Au</td>
<td></td>
<td></td>
<td></td>
<td>775-920</td>
<td></td>
<td>District overs 1,100 sq.km. and belongs to the water systems of the
Wusulijiang and Shuifenhe Rivers and their tributaires. The deposits are
alluvial, alluvial-proluvial valley flat and valley terrace types. Au
mainly derived from gold occurrence in metamorphic rock, Mesozoic
granite, and altered volcanic belts. Typical is the Jinchangtui placer
Au deposit in that gold ore bodies occur as bands or lenses. The grade
is relatively high. Associated minerals are galena and cassiterite. The
diameter of Au grains is usually less than 0.5mm.</td>
<td>Lu Yingjie and others, 1988.</td>
<td>China</td>
</tr>
<tr class="odd">
<td>L</td>
<td>54</td>
<td>01</td>
<td>45 02 03N</td>
<td>45.0341666666667</td>
<td>142 05 11E</td>
<td>142.086388888889</td>
<td>PGE, Cr, Au</td>
<td></td>
<td>Teshio</td>
<td>Placer PGE</td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td>District consists of alluvial PGE and Au placer deposits. The size
of the district is 60 km by 20 km, and is elongated NS. The deposits are
underlain mainly by serpentinite of Kamuikotan belt. The placer deposits
occur along the Makanbetu River. Main deposits in the district is at
Makanbetu-Hoshin. Heavy metals of deposits also contains 20-30% of Au.
Average grade is 0.4g / m2.</td>
<td>Suzuki, 1950; Geological Survey of Japan, 1955; Saito and others,
1967.</td>
<td>Japan</td>
</tr>
<tr class="even">
<td>L</td>
<td>54</td>
<td>02</td>
<td>45 02 16N</td>
<td>45.0377777777778</td>
<td>142 26 34E</td>
<td>142.442777777778</td>
<td>Au</td>
<td>PGE</td>
<td>Esashi</td>
<td>Placer and paleoplacer Au</td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td>District consists of alluvial placer deposits. The size of the
district is 25 km by 25 km. The placer deposits occur along Usotan,
Tonbetu, Peichan, and Horobetsu Rivers. Alluvial terrace deposits also
contain minor Au. The deposits are underlain by black shale of the Late
Jurassic to Early Cretaceous Sorachi Supergroup. Main deposits in the
district are at Usotan, Peichan, and Utanobori. A large nugget of Au
weighing 769 g was found at the Usotan deposit in 1900.</td>
<td>Saito and others, 1967.</td>
<td>Japan</td>
</tr>
<tr class="odd">
<td>L</td>
<td>54</td>
<td>03</td>
<td>47 57 37N</td>
<td>47.9602777777778</td>
<td>142 15 57E</td>
<td>142.265833333333</td>
<td>Au</td>
<td></td>
<td>Il'inka River</td>
<td>Placer Au</td>
<td>Small</td>
<td></td>
<td></td>
<td></td>
<td></td>
<td>Gold is fine-grained, 0.2 to 0.3 mm. Heavy-mineral concentrate
consists of chromite, epidote, and garnet. Small gold-cinnabar
occurrences are presumably sources for the placer. Deposit occurs along
the Il'inka River where it discharges into Tatar Strait. Alluvium of the
first (lowest) floodplain terrace is gold-bearing.</td>
<td>Sidorenko, 1977.</td>
<td>Russia</td>
</tr>
<tr class="even">
<td>L</td>
<td>54</td>
<td>04</td>
<td>47 48 00N</td>
<td>47.8</td>
<td>139 26 00E</td>
<td>139.433333333333</td>
<td>Ti</td>
<td>Sc, Rare Erth</td>
<td>Koppi-Nelman</td>
<td>Placer Ti</td>
<td></td>
<td></td>
<td>Beach placer with reserves of 1,125 thousand tonnes titanomagnetite,
submarine placer with reserves of 11.3 million tonnes of
titanomagnetite.</td>
<td></td>
<td></td>
<td>Occurs along sea shore of Tartar Strait. Two types of placer
deposits were explored. Sea-beach gravel, sandy-gravel, and sandy
material includes layers and lenses of placer titanomagnetite. The
placer is 100-1400 m long, 5-150 m wide, and 1 to 5 m thick.
Titanomagnetite content ranges from 8 up to 15%. Submarine placers are
near shore at shallow depth (up to 10 m). They are about 1000-6900 m
long, 100-600 m wide, and 2 to 20 m thick. Titanomagnetite content
varies from 3 up to 10%.</td>
<td>Onikhimovskiy and Belomestnykh, 1996.</td>
<td>Russia</td>
</tr>
<tr class="odd">
<td>M</td>
<td>46</td>
<td>01</td>
<td>49 30 00N</td>
<td>49.5</td>
<td>91 53 00E</td>
<td>91.05</td>
<td>Au</td>
<td></td>
<td>Burgastain-gol</td>
<td>Placer Au</td>
<td></td>
<td>100 to 2,000 mg/m3.</td>
<td>Proven reserves of 1.2 tonnes Au. Prognostic reserves of 5 tonnes
Au.</td>
<td></td>
<td></td>
<td>Occurs in western part of the Nuuryn metallogenic belt along the
major Tsagaanshiveet fault zone. Occurs in the Burgastain-gol River
Basin. Main placer Au deposits are at Burgastain-gol, Shuluun-bulag,
Talynsalaa, and Khorlhoitynzag. This placer deposits range from 1.0 km
to 7.0 km long, 50 m to 160 m wide, and 1.6 m to 9.0 m thick. Au-rich
strata is covered by up to 2.5 m barren sediment. The Shuluunbulag
placer was mined out in ancient time with extensive workings for 5.5 km.
Bedrock consists of Vendian to Early Cambrian marine volcanic, Silurian
sedimentary rock, and Devonian volcanic and sedimentary rock that are
intruded by a Devonian gabbro-granodiorite-granite intrusive complex.
The placer deposits belong to alluvial type. Placer Au is derived from
nearby lode occurrences of skarn and replacement Au.</td>
<td>O. Jamyandorj and others, written commun., 1977; N.L. Shubin and
others, written commun., 1985; L.V. Chistoedov and others, written
commun., 1991.</td>
<td>Mongolia</td>
</tr>
<tr class="even">
<td>M</td>
<td>48</td>
<td>01</td>
<td>49 25 00N</td>
<td>49.4166666666667</td>
<td>107 22 05E</td>
<td>107.368055555556</td>
<td>Au</td>
<td></td>
<td>Yoroo-gol</td>
<td>Placer Au</td>
<td></td>
<td>Average grade of 0.3 g/m3 to 2.46 g/m3 Au.</td>
<td>Production from 0.4 tonne in 1974; 0.37 tonnes in 1992, 0.47 tonnes
in 1993, 0.42 tonnes in 1994, and 1.3 tonnes in 1995; 9.7 tonne from
1974 within 1995; Proven reserves of 20 tonnes Au</td>
<td>880 to 960</td>
<td></td>
<td><p>Occurs in NE part of the North Khentii gold belt along the
Yoroo-gol and Khuder River basins. District strikes in NE direction, and
it occurs in the Yoroo-gol major fault zone. District is approximately
100 km long, and the width of the district ranges from 5 km to 15
km.</p>
<p>District is divided from NE to SW, in to the Khuder, Bugant-Tolgoit,
Ikh Altat and Yalbag subdistricts. Bedrock of the district consists of
regionally metamorphosed early Paleozoic terrigeneous formation of the
Kharaa Group that is intruded by early Paleozoic calc-alkaline rocks of
the Boroogol complex gabbro-granodiorite-granite complex, a middle
Paleozoic alkaline granite-leucogranite complex, and an early Mesozoic
gabbro-granodiorite-granite complex in small intrusives and dikes. Early
Cretaceous conglomerate with sedimentary gold occur locally. Most
placers of the district were discovered and mined out partly by
international Mongolor Mining Company that operated from 1900-1919. In
1926-1929 and 1939-1942, mining was renewed by the Mongolian government
in small scale. During 1960-1980, placer Au exploration occurred with a
proven reserve approximately 20 tonnes Au. Over 20 placer deposits were
discovered. Proven reserves are 30 kg to 7000 kg. Most are rediscovered
deposits. In 1974, former joint USSR and Mongolian Tolgoit placer Au
mining by the former SovMonTsvetmet company, nowadays the
MonRosTsevetmet joint venture, occurred in the Bugant-Tolgoit
subdistrict. The joint venture expanded into the Ikh-Altat subdistrist
in 1980's. Besides the joint venture, nowadays, extensive exploration is
being conducted by private Mongolian mining companies. All known placer
Au deposits are the alluvium type, but some parts of deposits are
man-made type.</p>
<p>The Khuder subdistrict occurs in the NE part of the district in the
upper part of the Khuder-gol River and tributary Tsagaanzur and Khyars
Rivers, and rivers valley such as the Buduun, Tsagaanshiluust, Buduun
and Galgatai that occur SW of the Khuder River valley. The Tsagaanzur
deposit was mined out, and the Khuder deposit partly by the Mongolor
Company. Mining activity in the Khuder deposit was renewed in last few
years. The valleys of the Khyars, Buduun, Tsagaanshiluust, Shorgoolj,
and Galgatai Rivers are expecting additional exploration. The average
fineness of gold of the Khuder placer is 960 (highest in the Yoroo-gol
district). Gold grains range from 0.25 mm to 1.0 mm (approximately 90%)
in the deposit. A significant primary source of Au has not be
discovered.</p>
<p>The Bugant-Tolgoit subdistrict occurs in the middle part of the
Yoroo-gol district along the sublatitudinal Bugant River basin and
northern and southern tributary valleys. Most proven reserves of placer
Au deposits of the Yoroo-gol district are concentrated in the
subdistrict. The larger but lower grade (the average 0.3 g/m3) deposit
is at Tolgoit with proven reserves of approximately 7 tonnes Au. Grade
ranges from 1.0 g/m3-2.46 g/m3 Au with up to 540 kg proven Au reserves.
The known deposits range from 0.5 km to 8.0 km long, from 20 m to 300 m
wide, and 1.1 m to 18 m thick. Some are covered by 2.9-12 m thick barren
sediment. The fineness of Au ranges from 894 to 960; Au fineness is
approximately 854 in placer deposits in valleys of southern tributaries
of the Bugant River, and ranges from 893 to 960 in placers in valleys of
northern tributaries. Significant primary source of Au is not known;
however, deposits occur in local bedrock and in small occurrences in
surrounding mountains. Most small size, high-grade placers were mined
out completely by 1974 by the Mongolian-Russian joint venture. Au from
of the larger Tolgoit placer has been mined from 1974 to the
present.</p>
<p>The Ikh-Altat subdistrict occurs SW of the Bugant-Tolgoit
subdistrict, along the longitudinal oriented middle Yoroo-gol River, and
eastern and western tributaries, including the Buural, Altan, Galt, Ikh
Ajir, and Baga Ajir. The large deposits, containing from 1880-2989
tonnes, but lower grade (0.25-0.31 g/m3) are at Ikh Altat and Ikh Ajir.
The Ikh Altat and Ikh Ajir deposits are respectively 7.4 km and 4.0[m
long, average 183 m and 175 m wide, and average 8.6 m and 8.8 m thick.
Others are 0.8-3.7 km long, 30-70 m wide, approximately 1.0 m thick, and
are covered by 3.1-44.0 m thick barren sediments. The deposits were
mined out by the MonRosTsevetMet joint venture. Fineness of Au ranges
from 841 to 884. Significant primary source of Au is not known; however
gold quartz veins occur in bedrock in the upper part of the Buural Au
placer.</p>
<p>The Yalbag subdistrict occurs in SW marginal part of the Yoroo-gol
district in the valleys of the Yalbag River and NW tributary, including
the Yoroo-gol River valley. They vary from 0.4-4.6 km long, 30 m to 155
m wide, from 1.0 m to 1.6 m thick, and covered by 2.2-6.2 m of barren
sediment. The grade of Au ranges from 1.2 g/m3 to 2.4 g/m3. Proven Au
reserves ranges from 30 kg to 1417 kg. The fineness of Au grains ranges
from 870 to 906. One of primary sources of Au is a weak gold-bearing
weak zone in bedrock of the Yalbag deposit.</p></td>
<td>Usov, 1914; V.G. Bubennikov and others, written commun., 1962;
Bolotova, 1966; Tegshil, 1968; N.S. Vidyakin and others, written
commun., 1969; A.M. Yurlov and others, written commun., 1970; V.P. Larev
and others, 1971; Mormily and others, 1971; A.M. Yurlov and others,
written commun., 1971; Renchin and others, 1973; Jambaa and others,
1975; Chesnyakov and others, 1976; Semenov and Noov, 1976; Semenov and
others, 1976; Blagonravov and Shavolovskyi, 1977; D. Bat-Erdene and
others, written commun., 1979, 1982; Ts. Gombosuren, written commun.,
1979, 1983; L. Basarsad and others, written commun., 1981, 1982, 1984;
N. Nyam and others, written commun., 1981; V. Dovjid and others, written
commun., 1981; D. Gungaanyam and B. Bold-Erdene, written commun., 1984;
D. Gungaanyam and others, 1981; B. Bold-Erdene, written commun., 1986;
Semeikhan, 1989; Jamsrandorj and others, 1996.</td>
<td>Mongolia</td>
</tr>
<tr class="odd">
<td>M</td>
<td>48</td>
<td>02</td>
<td>49 19 00N</td>
<td>49.3166666666667</td>
<td>106 45 00E</td>
<td>106.75</td>
<td>Au</td>
<td></td>
<td>Sharyn-gol-Bukhlei</td>
<td>Placer Au</td>
<td></td>
<td>Average grade of 0.9 g/m3 to 2.5 g/m3 Au.</td>
<td>Production of 0.3 tonnes Au in 1994. Reserves of 10 tonnes Au.</td>
<td>778 to 894</td>
<td></td>
<td><p>Occurs in NE part of the North Khentii gold belt in the
Bukhlei-gol and Sharyn-gol River basins. District strikes NE and occurs
along the major Bayangol-gol fault zone. District is approximately 50 km
long, and from 15 km to 20 km wide.</p>
<p>District is divided from NE to SW, into the Bukhlein-gol,
Khuiten-gol, and Sharyn-gol subdistricts. Bedrock of the district
consists of early regionally metamorphosed Paleozoic terrigeneous rock
of the Kharaa group that is intruded by early Paleozoic calc-alkaline
Boroogol complex containing gabbro, granodiorite, and granite, a middle
Paleozoic alkaline granite-leucogranite complex, and an early Mesozoic
gabbro-granodiorite-granite complex with small intrusives and dikes.
Early Cretaceous conglomerate with clastic sedimentary gold, occur
widely. Some placer Au deposits were discovered and mined out partly by
international Mongolor mining company that operated in 1900-1919. During
1970-1980, placer Au exploration again occurred with new proven reserves
of approximately 10 tonnes Au. Over 10 placer deposits were discovered.
Proven reserves ranges from 100 to 3200 kg. Most are rediscovered
deposits. Placer Au deposits are being mined intensively by private
Mongolian mining companies. All known placer deposits are the alluvium
type, but some are man-made. Primary source of is vein and replacement
type Au, and conglomerate and clastic sedimentary Au. One small quartz
Au vein deposit occurs in bedrock of the Baga-Noyon placer deposit, and
was explored and mined out by Mongolor joint venture in 1912-1914. Most
known vein and replacement Au prospects are deeply eroded. Placer Au in
many deposits is derived from nearby Cretaceous conglomerate with
clastic sedimentary Au.</p>
<p>The Bukhlein-gol subdistrict occurs in NE part of the
Sharyn-gol-Bukhlei district, in the upper part of the Bukhlein-gol River
basin along the Khargana, Olont, Tsamkhag the Mogoi Rivers. Known placer
deposits are approximately 5 km long, 100 m wide, and 1.5 m to 4.3 m
thick, and are covered by barren Quaternary sediments with a thickness
of 3.2 to 12.5 m. Average grade is approximately 1.0 g/m3 Au.</p>
<p>The Khuiten-gol subdistrict occurs in the middle part of the
district, along the upper part of the Kuiten gol River and eastern
tributaries the Baga-Noyon and the Ikh-Noyon Rivers. The largest is the
Khuiten placer Au deposit with average grade of 1.2 g/m3 Au. The deposit
is 12.4 km long, 45 m wide, 1.2 m thick, and is covered by barren
Quaternary sediments that average 3.5 m thick.</p>
<p>The Sharyn-gol subdistrict was discovered in 1984-1990. The
subdistrict occurs in SW margin of the Sharyn-gol River valley, and NE
tributaries of the Shaazgait, Khavchuu, and Burkhant Rivers. Known
deposits have proven Au reserves from 100 kg to 3200 kg with an average
grade from 0.9 to 2.5 g/m3 Au, range from 0.8-3.0 km long, and average
70 m to 150 m wide and 2.5 m to 3.0 m thick. They are covered by barren
Quaternary sediment with an average thickness of 4.0 to 12.0 m. Most
placer Au deposits have two Au-rich horizons; the lower horizon is
mostly buried under the upper horizon. Most primary Au sources are vein
and replacement types, are deeply eroded, with Au is deposited in Early
Cretaceous conglomerate. Placer Au in most deposits is derived from
nearby Early Cretaceous conglomerate.</p></td>
<td>Usov, 1914; Bolotova, 1966; Tegshil, 1968; Jambaa and others., 1975;
Mormily and others, 1971; Renchin and others, 1973; L. Basarsad and
others., written commun., 1979; B. Bold-Erdene and others., written
commun.,1985; Gmitron and others., 1976; Ts. Gombosuren, written
commun., 1979, 1983, 1986; Gromov and others., 1971; Blagonravov and
Shavolovskyi., written commun., 1977; D. Gungaanyam, written commun.,
1981; D. Gungaanyam and L. Basarsad, written commun., 1981; D.
Gungaanyam and B. Bold-Erdene, written commun., 1984; N. Nyam and
others., written commun., 1984; Semeikhan, 1989; Jamsrandorj and others,
1996.</td>
<td>Mongolia</td>
</tr>
<tr class="even">
<td>M</td>
<td>48</td>
<td>03</td>
<td>48 32 05N</td>
<td>48.5347222222222</td>
<td>106 45 00E</td>
<td>106.75</td>
<td>Au</td>
<td></td>
<td>Boroo-Zuunmod</td>
<td>Placer Au</td>
<td></td>
<td>Average grade of 1.0 g/m3 Au.</td>
<td>Production of 0.5 tonnes in 1993 to 1995. Reserves of 10 tonnes
Au,</td>
<td>850 to 900</td>
<td></td>
<td><p>Occurs in the middle part of the North Khentii Au belt in upper
western part of the Kharaa-gol River basin. Occurs at the intersection
of NE-trending major Yoroo-gol fault zone and NW-trending Nariin-khondii
fault system. District is 65 km long (NE direction), and 45 km wide (NW
direction). The bedrock consists of the early Paleozoic the Kharaa Group
that contains terrigeneous rock intruded by a Ordovician
gabbro-granodiorite-granite complex, a Devonian granite batholith and
coeval rhyolite subvolcanic bodies and dikes, and an early Mesozoic
gabbro-granodiorite-granite complex with small intrusives and dikes.</p>
<p>District is divided in to the Boroo, Zuunmod and the Borkhujiryn-gol
subdistricts. The largest placer deposits are at Ikh Tashir and
Gachuurt. Most placer deposits were discovered in 1985-1995. Direct
exploration guides of placer Au deposit in the area around the Au the
Boroo lode deposit and in other places, were known from 1955, but
significant exploration on placer Au only occurred after 1985. Au in
most known placer deposits is derived from nearby lode gold deposits.
Placer Au deposits are the complicate eluvial-deluvial-proluvial,
eluuvial-alluvial, and eluvial-deluvial-alluvial types. Placers formed
during two periods, Pliocene, and Quaternary. First period placers are
mostly buried under very thick (up to 50 m) Quaternary sediments, and
second period placers are closely related to late Quaternary to Holocene
and Holocene elluvial, deluvial, proluvial and alluvial deposits.</p>
<p>The Boroo subdistrict occurs in NW part of the Boroo-Zuunmod
district, and is related to nearby lode Au deposits. The largest is at
Ikh Tashir. The primary source is the eastern Boroo vein and replacement
deposit. The placer deposit has two Au rich strata. The lower and the
upper strata occur together in the upper part of the placer deposit, but
the middle and lower parts of these strata are separated vertically and
horizontally. The lower strata occurs in red and red-yellow Pliocene
proluvial-alluvial deposits with an average thickness of 1.0 m. The
middle and the lower parts of the upper strata occurs in proluvial
deposits of the Ikh Tashir valley. The upper part of the placer deposit
occurs in thick (up to 15 m) eluvial-deluvial-proluvial deposits that
consist of red and red-yellow Pliocene eluvial-deluvial deposits in the
lower part, and Late Quaternary to Holocene eluvial-deluvial-proluvial
deposits in upper part. The upper part of the deposit is being mined by
a private Mongolian company. The proven reserve of Au is approximately
4.0 tonnes with an average grade of 1.3 g/m3 Au.</p>
<p>The Zuunmod placer Au subdistrict occurs in SE marginal part of the
Boroo-Zuunmod district and is closely a local lode deposit. The
subdistrict occurs along the NE-trending major Yoroo-gol fault zone. The
largest placer Au deposits is at Gachuurt that occurs along a
NE-trending valley along the major Yoroo-gol fault zone that controls
both the Boroo-Zuunmod hard rock and placer Au ore district. This fault
zone contains the Sujist lode Au ore-field. Bedrock consists of early
Paleozoic granodiorite and granite, and Devonian subvolcanic rhyolite
that are strongly foliated and altered. Placer Au and prospects are
alluvial type.</p>
<p>The Borkhujiryn-gol subdistrict occurs in southern marginal part of
the Boroo-Zuunmod district, and also along the major Yoroo-gol fault
zone. Known placer Au prospects are proluvial-alluvial hybrid, and
alluvial types. The subdistrict is related closely to the nearby lode Au
ore field.</p></td>
<td>V.N. Loginov, written commun., 1958; Blagonravov and Shavolovskyi,
1977; Jamsrandorj and others, 1996; Semeikhan, 1989.</td>
<td>Mongolia</td>
</tr>
<tr class="odd">
<td>M</td>
<td>48</td>
<td>04</td>
<td>48 32 05N</td>
<td>48.5347222222222</td>
<td>104 32 05E</td>
<td>104.534722222222</td>
<td>Au</td>
<td></td>
<td>Zaamar</td>
<td>Placer Au</td>
<td></td>
<td>Average grade of 0.5 g/m3 to 2.0 g/m3 Au.</td>
<td>Production: of 1.4 tonnes Au in 1990-1994. Proven reserves: of 82
tonnes Au and prognostic resource 18 tonnes Au.</td>
<td>900</td>
<td></td>
<td>Occurs in SW part of the North Khentii Au belt along NE-trending the
major Bayan-gol fault zone. Both lode and placer Au deposits and
prospects occur. District extends NE-SW, is approximately 100 km long
and 15 km wide. District was explored in 1982-1990. Most economical
placer Au deposits occur along NW slope of Zaamar Mountain range, Tuul
River valley, and in tributaries. District is underlain by the early
Paleozoic the Kharaa Group of terrigeneous rock, early Paleozoic and
Devonian granitoids, Carboniferous and Permian sedimentary clastic rock,
early Mesozoic variable composition dikes, and Early Cretaceous
conglomerate. Cenozoic sediments occur mostly in the Tuul River and
tributaries. District contains notable examples of placer Au deposits.
River basins of the district, are filled mostly with Neogene red,
clay-rich deposits, and Quaternary sand and clay beds. Placer deposits
are multi-stream and multi-stratal. Deposits are lenticular, vary from
80 m to 160 m wide, up to 10 m thick. Concentration of Au started in
Pliocene with most forming in Quaternary sedimentary deposits, directly
overlying greenschist facies metamorphosed rock of the early Paleozoic
Kharaa Group. Sediment reworking along the Tuul River and SE tributaries
resulted in redistribution and local enrichment of placer deposits. The
largest placer Au deposits in the district are the Tuul (average grade
of 528mg/m3 to 791 g/m3; and 21197 kg Au reserve), the Bayangol (average
grade of 401 to 569 mg/m3; and 5757 kg Au reserve), and the Khailaast
(average grade 2460 mg/m3; and 5721 kg Au reserve).</td>
<td>Alkin and others, 1989; Jamsrandorj, 1987; Jamsrandorj and
Diatchkov, 1996; Semeikhan, written commun., 1989.</td>
<td>Mongolia</td>
</tr>
<tr class="even">
<td>M</td>
<td>49</td>
<td>01</td>
<td>49 01 00N</td>
<td>49.0166666666667</td>
<td>110 15 00E</td>
<td>110.25</td>
<td>Au</td>
<td></td>
<td>Baljiin-gol</td>
<td>Placer Au</td>
<td></td>
<td>Average grade of 312 mg/m3 to 1,140 mg/m3 Au..</td>
<td>Reserves of 50 tonnes Au.</td>
<td></td>
<td></td>
<td>Occurs in NE part of the South Khenii metallogenic belt near Russia
along Balj-Gol River and northern tributaries. Main placer Au
occurrences are at Khomol-gol, Khavirgan, Baruunkhuurain-gol,
Chahal-gol, and Galgatai-gol. Placer Au occurrences range from 1.5 km to
4.0 km long, 40 m to 1.0 km wide, and 2.0 m to 6.0 m thick. Bedrock
consists of early Paleozoic clastic rock intruded by Mesozoic
granitoids. Lode Au occurrences are granitoid-related Au vein and
replacements.</td>
<td>Blagonravov and Shavolovskyi, 1977; J. Byamba, written commun.,
1990.</td>
<td>Mongolia</td>
</tr>
<tr class="odd">
<td>M</td>
<td>49</td>
<td>02</td>
<td>48 31 00N</td>
<td>48.5166666666667</td>
<td>108 29 00E</td>
<td>108.483333333333</td>
<td>Au</td>
<td></td>
<td>Terelj</td>
<td>Placer Au</td>
<td></td>
<td>Range of 312 mg/m3 to 1140mg/m3 Au.</td>
<td>Prognostic reserves of 50.0 tonnes Au.</td>
<td></td>
<td></td>
<td>Occurs in the middle part of the South Khentii metallogenic belt in
the upper parts of the Tuul and Kherlen Rivers. Main placer deposit is
at Altansuudal in Altansuudal River valley that is one of NE tributaries
of the Kherlen River. It averages 3.0 km long, 80-100 m wide, and 1.7 m
thick. The placer is covered by 2.2 m thick barren sediment. Bedrock
consists of Devonian and Carboniferous terrigenous rock intruded by
Mesozoic granite rock. The primary source of placer Au is not
known.</td>
<td>Blagonravov and Shavolovskyi, 1977; B.V. Shekin and others, written
commun., 1985.</td>
<td>Mongolia</td>
</tr>
<tr class="even">
<td>M</td>
<td>49</td>
<td>03</td>
<td>49 31 00N</td>
<td>49.5166666666667</td>
<td>113 15 00E</td>
<td>113.25</td>
<td>Au</td>
<td></td>
<td>Turgen</td>
<td>Placer Au</td>
<td></td>
<td>Average grade from 100 mg/m3 to 1000mg/m3 Au.</td>
<td>Production: 0.0 tonne Proven reserves: of 0.5 tonne Au</td>
<td></td>
<td></td>
<td>Occurs in NE part of the Khoit Kherlen metallogenic belt in northern
tributaries of the latitudinal part of the Ulz River. Major placer Au
deposits are at Tsagaanchuluut-khudag, Tsagaanchuluut-khooloi,
Gun-Ondoriin-khooloi, Arshaant, and Ovoljoon. Proven reserves range from
0.1 to 4.0 tonnes Au. The Tsaganchuluut-khudag deposit is being mined.
Bedrock consists of Paleoproterozoic metamorphic rock with younger early
Paleozoic, late Paleozoic, and Mesozoic intrusives. Placer Au is derived
from nearby lode Au occurrences. The placers occur mainly in two Au rich
strata, vary from 1.0 km to 8.0 km long, 40 m to 160 m wide, and 0.5 m
to 4.0 m thick. The Au rich upper strata are covered by approximately
1.5-3.0 m of barren sediments. The upper Au-rich strata are alluvial
-proluvial, and the lower Au-rich strata is alluvial type.</td>
<td>B. V. Shekin and others, written commun., 1985.</td>
<td>Mongolia</td>
</tr>
<tr class="odd">
<td>M</td>
<td>49</td>
<td>04</td>
<td>48 20 00N</td>
<td>48.3333333333333</td>
<td>112 28 00E</td>
<td>112.466666666667</td>
<td>Au</td>
<td></td>
<td>Narsynkhondlon</td>
<td>Placer Au</td>
<td></td>
<td>Average grade of 200 mg/m3 to 1,000 mg/m3 Au.</td>
<td>Production: of 0.2 tonnes Au. Proven reserves of 1.0 tonnea Au.
Prognostic reserves of approximately 5.0 tonnes Au.</td>
<td>850</td>
<td></td>
<td>Occurs in the middle part of the Khoit Kherlen metallogenic belt.
Bedrock consists of Devonian, Carboniferous, and Permian volcanic and
sedimentary rock with Devonian, Permian and Mesozoic intrusive rock.
Main placer Au deposits are at Salkhit and Tokhoi. Deposits are
proluvial type, vary from 0.5 to 1.0 km long, 40-80 m wide, and 2.5 m to
4.0 m thick. Deposits have being mined.</td>
<td>S. Ch. Norobsambuu and others, written commun., 1987; O.
Nasantogtokh and others, written commun., 1994; Ts. Gombosuren and
others, written commun., 1995.</td>
<td>Mongolia</td>
</tr>
<tr class="even">
<td>M</td>
<td>49</td>
<td>05</td>
<td>49 13 00N</td>
<td>49.2166666666667</td>
<td>109 06 00E</td>
<td>109.1</td>
<td>SnO2</td>
<td>(Mn,Fe)WO4</td>
<td>Deed Kumiir</td>
<td>Placer Sn</td>
<td></td>
<td>Averade grade of 887g/m3 SnO2 . Average grade of 1,130 g/m3 WO4</td>
<td>Reserves of 1,277 tonnes SnO2. Reserves of 1,022 tonnes WO4.</td>
<td></td>
<td></td>
<td>More than three placer deposits occur near the Deed Kumiir
tin-tungsten lode deposit, in an area of moderate relief. Placer
deposits are alluvial, valley-fill, deeply-buried, and complex types.
Tin and wolframite occur in commercial concentrations. Heavy minerals
are cassiterite, scheelite, and wolframite. Placer deposits occur in
first- to second-order streams and formed from late Pleistocene to
Holocene. Placers are characterized by relatively contstant thickness of
stratum. Thickness economic gravels ranges from 1.5 to 2.5 m. Sn-W lode
deposits at Deed Kumiir, Tom Zelenga, and other
cassiterite-tungsten-quartz deposits are source of placer deposits.</td>
<td>K.D. Pomazkov, written commun., 1944; N.M. Khrenov, written commun.,
1946; Ts. Tseden., written commun., 1980; Khasin and Suprunov,
1977.</td>
<td>Mongolia</td>
</tr>
<tr class="odd">
<td>M</td>
<td>49</td>
<td>06</td>
<td>49 06 30N</td>
<td>49.1083333333333</td>
<td>109 29 30E</td>
<td>109.491666666667</td>
<td>SnO2</td>
<td></td>
<td>Zuuntarts</td>
<td>Placer Sn</td>
<td></td>
<td>Averade grade of 500 g/m3 SnO2.</td>
<td>Reserves of 7,090 tonnes SnO2.</td>
<td></td>
<td></td>
<td>Consists of two placer deposits in the upper Onon district that
occur at the boundary between late Paleozoic and Jurassic granitoids.
Placer deposits occur in first-to third-order streams as buried alluvial
thalwegs. Pay zones in placer deposits extend for 1 km and at 1 to 2 m
depth. Minor wolframite occurs in along with cassiterite. The Zuuntarst
and Big Zilenda cassiterite-quartz vein lode deposits are the principal
lode source for the placer deposits. Cassiterite concentration ranges
from 156 g/m3 to 417 g/m3 and wolframite concentration ranges from 13
g/m3 to 56 g/m3.</td>
<td>N.I. Khomizurin and others., written commun., 1952; Khasin and
Suprunov, 1977; Ts. Tseden., written commun., 1989.</td>
<td>Mongolia</td>
</tr>
<tr class="even">
<td>M</td>
<td>52</td>
<td>01</td>
<td>49 10 00N</td>
<td>49.1666666666667</td>
<td>130 55 00E</td>
<td>130.916666666667</td>
<td>Au</td>
<td></td>
<td>Malokhingansky (Malokhingan) district</td>
<td>Placer Au</td>
<td></td>
<td></td>
<td>Production of 4.0 tonnes Au. Proven reserves of 1.0 tonne Au.
Inferred reserves of 18.0 tonnes Au.</td>
<td></td>
<td></td>
<td><p>District divided into the Nizhnebureisky and Arkharinsky
subdistricts. The largest lode deposit in the area is at Prognoznoe in
the Nizhnebureisky subdistrict. This deposit was discovered in 1972
during geologic mapping. Small placers (Simichi River and Gniloi Spring)
were discovered in 1972 near the Prognoznoe lode deposit. Placer gold is
derived from nearby lode deposits.</p>
<p>Arkharinsky subdistrict occurs in the SE part of the Malokhingansky
district. Bedrock is mainly early Paleozoic and early Mesozoic granitic
rock. Neogene to Quaternary basalt locally overlies unconsolidated
Cenozoic deposits in the headwaters of the Maly Bira and Uril Rivers.
Estimated placer gold potential wasconsidered high at the beginning of
previous century. Richest placers were mined along the Maly Bira River.
Undiscovered placer deposits may occur beneath the basalt. Deposits as
at Paskhalny Spring were completely mined out by underground mining in
the 1950's. Mesozoic and Cenozoic sedimentary units may also contain
older placer deposits.</p></td>
<td>V.D. Melnikov and others, written commun., 1985.</td>
<td>Russia</td>
</tr>
<tr class="odd">
<td>M</td>
<td>52</td>
<td>02</td>
<td>50 50 00N</td>
<td>50.8333333333333</td>
<td>127 25 00E</td>
<td>127.416666666667</td>
<td>Au</td>
<td></td>
<td>Blagoveshchensk-Svobodnensky district</td>
<td>Placer Au</td>
<td></td>
<td></td>
<td>Production of 1.0 tonnes Au. Proven reserves of 0.0 tonnes Au.
Inferred reserves of 10.0 tonnes Au.</td>
<td></td>
<td></td>
<td>Occurs in an area adjacent to the Amur River from the city of
Blagoveshchensk to the village of Chenyaevo, and along the Zeiya River
from the mouth to the Selemdzha River. Area is overlain mostly by
unconsolidated deposits of the Amur-Zeiya valley. Bedrock crops out
occur near the Amur River and is part of the Norsk-Sukhotinsky terrane.
Placer gold deposits in the district have been known since the beginning
of the previous century when prospectors started operations on bars and
islands of the Amur and Zeiya Rivers. The Surazhevka bar placer in the
Zeiya River, near the town of Svobodny, has been mined. The most
promising area for placer deposits is the northern bank of the Amur
River from the city of Blagoveshchensk to the village of Ushakovka. This
area continues into China, on the opposite bank of the Amur River into
the Fabelakhe subdistrict.</td>
<td>Dzu Sung, 1991; V.D. Melnikov and others, written commun.,
1989.</td>
<td>Russia</td>
</tr>
<tr class="even">
<td>M</td>
<td>52</td>
<td>03</td>
<td>51 55 00N</td>
<td>51.9166666666667</td>
<td>131 55 00E</td>
<td>131.916666666667</td>
<td>Au</td>
<td></td>
<td>Turansky district</td>
<td>Placer Au</td>
<td></td>
<td></td>
<td>Production of 0.3 tonnes Au. Proven reserves of 6.0 tonnes Au.
Inferred reserves 29.0 tonnes Au.</td>
<td>937</td>
<td></td>
<td>Occurs in the Turansky subterrane of the Bureya terrane. District is
divided into the Byssinsky, Ulmiisky, and Aleunsky subdistricts. Only
the Byssinsky subdistrict is economic. The only lode source is the
unexplored Buyanovsky occurrence. Bedrock consists of Precambrian
metamorphic rock overlain by Early Cretaceous volcanic rock. A large
placer was discovered on the Sinnikan River and tributaries. Length is 9
km, average width is 80 m, thickness of economic bed is 0.54 m, and gold
grade in economic bed is 1059 mg/m3. Proven reserves of the placer are
980 kg. Tributaries of the Sinnikan River have potential for
undiscovered deposits.</td>
<td>V.D. Melnikov and others, written commun., 1989.</td>
<td>Russia</td>
</tr>
<tr class="odd">
<td>M</td>
<td>52</td>
<td>04</td>
<td>50 05 00N</td>
<td>50.0833333333333</td>
<td>126 40 00E</td>
<td>126.666666666667</td>
<td>Au</td>
<td>Garnet</td>
<td>Huma</td>
<td>Placer Au</td>
<td>Large</td>
<td>Average grade of 0.1 to 9 g/m3 Au.</td>
<td>Production of 125 tonnes Au from 1970-1995.</td>
<td>845</td>
<td></td>
<td>District covers 40,000 km2 along the Heilongjiang River and
tributaries, including Huma, Fabiela, Lunjiang, Menluhe, and Keluo
Rivers. Permafrost occurs in the area. Placer deposits in modern and
small valleies have greater economic significance. Gold mainly derived
from the lode gold and vein deposits that are widely developed in the
Proterozoic metamorphic bedrock, Paleozoic granite, and Jurassic
volcanic rock. Thee Dalahan placer deposit is representative and
contains ore bodies that are single-layered and banded, and occur along
a river valleyThe deposit is alluvial valley type and is redeposited
from drift sediments. Au grain size is 0.2-0.5 mm, with common local Au
grains of 2.00 mm. Associated minerals are ilmenite, magnetite, pyrite,
tourmaline, and garnet. Garnet locally abundant. Mining started in about
1860.</td>
<td>Lu Yingjie and others, 1988; Chen Jiming and others, 1997</td>
<td>China</td>
</tr>
<tr class="even">
<td>M</td>
<td>54</td>
<td>01</td>
<td>50 48 34N</td>
<td>50.8094444444444</td>
<td>139 36 41E</td>
<td>139.611388888889</td>
<td>Au</td>
<td></td>
<td>Oemku</td>
<td>Placer Au</td>
<td>Small</td>
<td></td>
<td></td>
<td>800-850</td>
<td></td>
<td>Occurs in stream deposits of the Oemku River and other northern
tributaries of the Muli River that flow into the Tumnin River.
Gold-bearing beds contain fine- and medium-grained gold. Gold is derived
from the Oemku lode deposit that contains gold-rich quartz veins. Local
bedrock is Early Cretaceous siltstone and sandstone.</td>
<td>A.M. Peshkov, written commun., 1972.</td>
<td>Russia</td>
</tr>
<tr class="odd">
<td>M</td>
<td>54</td>
<td>02</td>
<td>50 10 07N</td>
<td>50.1686111111111</td>
<td>142 57 07E</td>
<td>142.951944444444</td>
<td>Au</td>
<td></td>
<td>Langeriiskoe</td>
<td>Placer Au</td>
<td>Medium</td>
<td></td>
<td></td>
<td>879-932</td>
<td></td>
<td>Occurs in several river valley placers that range from 1000 to 7200
m long and 20 to 30 m wide. A zone of alluvium, from 1.8 to 2.0 m thick
adjacent to bedrock, is most enriched in gold. Gold grains range from
less than 0.5 mm (30%), 0.5 to 1.0 mm (33%), 1.0 to 2.0 mm (26%), to 2.0
mm (11%). Chromite, pyrite, zircon, rarely cinnabar, scheelite,
arsenopyrite, galena, and hematite also occur in heavy concentrates.
Placer gold is derived from Au quartz vein deposits in quartz-micaceous
schist.</td>
<td>Sidorenko, 1977.</td>
<td>Russia</td>
</tr>
<tr class="even">
<td>N</td>
<td>51</td>
<td>01</td>
<td>55 40 00N</td>
<td>55.6666666666667</td>
<td>125 00 00E</td>
<td>125</td>
<td>Au</td>
<td></td>
<td>Verkhneselemdzha</td>
<td>Placer Au</td>
<td></td>
<td></td>
<td>Production of 5 tonnes Au. Proven reserves of 6 tonnes Au. Inferred
reserves of 55 tonnes Au.</td>
<td></td>
<td></td>
<td><p>District is the best known placer district in the Amur region and
includes the Kharga, Malomyrsky, Verkhnestoibinsky, and Tokur-sagursky
subdistricts. Total inferred reserves for the district are 226 tonnes
gold, 13.7% of the total reserves of the Amur region. The majority of
mined lode gold deposits also occur in this district (Zazubrinsky,
Poiskovoe, Sagur, Afanas'evsky, Kharga, Unglichikan, and Yasnoe). Most
lode gold deposits occur in metamorphic rock. District includes large
placers that can be mined by dredge (Selemdzha River, Verkhny and Nizhny
Stoiba, Kharga, Maly Naergen, Elga, Semertak, Ugokhan, and Bolshoi, and
Maly Karaurak). Placer mining began in 1972 and continues.
Nizhneselemdzha (Maisky) gold-bearing subdistrict covers the areas near
the mouths of the Orlovka, Selemdzha, and Aldikon Rivers. Most placers
occur in the Neklya River valley. Placer mining began in 1895 and
continues. Bedrock consists of metamorphic rock, mainly Silurian schist
cut by large early Paleozoic granitoid intrusions. The largest placer in
the subdistrict is on the Neklya River and consists of shallow- and
deep-seated gold-bearing beds. This placer has been mined since 1902 and
has produced 9.5 tonnes gold. The placer occurs between two granitic
stocks (Tatarkinsky in the north and Ust-Orlovsky in the south) early
Paleozoic schist inbetween. An economic placer that is 15 km long and
averages 140 m wide occurs in the headwaters and middle part of the
Neklya River valley. In the upper part of this deposit, the first
gold-bearing layer is 1.5 m thick and occurs at 6-8 m below the surface.
Downstream, the deposit splits into two beds with a bed of gold-free
alluvium 10-12 m thick between. The beds coincide in plan view. A
paleoplacer plunges to the south and has been explored to a depth of 24
m. Gold-bearing deposits consist of quartz pebble and cobble gravel with
a compact clay matrix. Average gold grade in being mined at present is
115 mg/m3, and fineness of native gold is 900. Gold is fine and average
size is 0.64 mm. Most gold in placers is dense, but several dendritic
grains occur. Unlike the lower bed, the upper one has smaller gold
grains that are poorly rounded. Poorly-rounded nuggets intergrown with
quartz also occur. Fragments of veined quartz found in headwaters of the
Neklya River, contain up to 2.4 g/t gold. The placer is presently being
mined with a dredge.</p>
<p>Malomyrsky subdistrict is small, but gold grades are high. It also
includes the medium-sized Malomyr lode deposit. The largest placer
occurs on the Nizhny Stoiba River. Verkhne-Stoibinsky placer subdistrict
includes two small lode gold deposits (Pokrovka and Voroshilovka) and
large placers in the valley of the Verkhny Stoiba River. Gold is mainly
concentrated near granitoid intrusions and lode sources.</p>
<p>Tokur-Sagursky subdistrict includes several deposits. The Tokur lode
deposit and several rich placers in the headwaters of the Bolshoi
Karaurak and Tarnakh Rivers occur in the northern part of the
subdistrict. Numerous small lode occurrences in greenschist facies
metamorphic rock and small placer deposits occur in the middle part of
the Bolshoi and Maly Karaurak Rivers. Some placer deposits occur within
the Sagur dome-like structure. The largest placer at Koboldinsky occurs
in the Koboldinsky part of the Selemdzha River between the Ogodzha and
Maly Karaurak Rivers. The Sagursky lode deposit occurs to the east, and
bedrock near this deposit contains numerous metamorphic gold
occurrences. To the west of the placer are promising lode gold deposits
(Pridorozhnoe and Mostovoe).</p>
<p>Kharga subdistrict contains six small Au and Au-W lode deposits and
one Au-Sb lode deposit. Three placer gold-bearing areas are
distinguished and occur in metamorphic domes and outcrops of small
intrusions. The Kharga placer is the largest in the subdistrict and
produced over 20 tonnes. Au was produced from valley part of the
deposit. This deposit has several lode sources. The richest part of the
placer occurs close to the Kharga lode deposit. Numerous metamorphic
gold occurrences with high gold grades occur the placer. The upper part
of the Kharga Creek valley was recently explored. The richest part of
the placer occurs immediately adjacent to the Talyminsky Au-Sb lode
deposit.</p></td>
<td>V.D. Melnikov, written commun., 1990.</td>
<td>Russia</td>
</tr>
<tr class="odd">
<td>N</td>
<td>51</td>
<td>02</td>
<td>54 53 00N</td>
<td>54.8833333333333</td>
<td>124 15 00E</td>
<td>124.25</td>
<td>Au</td>
<td></td>
<td>Srednenuykzhinsk</td>
<td>Placer Au</td>
<td></td>
<td></td>
<td>Production of 23 tonnes Au. Proven reserves of 25 tonnes Au.
Inferred reserves of 76 tonnes Au.</td>
<td></td>
<td></td>
<td><p>Srednenyukzhinsky district contains three gold-bearing
subdistricts - Elgakan, Urkimin, and Dzheltulak. Elgakan subdistrict
occurs on the western side of the Nyuksha River. Several small
hydrothermal lode gold occurrences occur in this area; including
Balykhtakh that occurs along a EW-trending fault bounding the southern
edge of the Mesozoic Chilchinsky granitic pluton. Only low-grade gold
placer deposits occur.</p>
<p>Urkimin subdistrict occurs on the eastern side the Nyuksha River. The
Dzheltula and Sredny Larba placer deposits occur in the Dzheltulak
(Burpalin) fault zone that separates metamorphic rock to the north from
the Anosov pluton to the south. Placers of the Urkimin subdistrict are
extremely high-grade. They include large prospected placers along the
Urkima, Onon, Odolgo, and Agin Rivers, presently being mined by dredges,
and smaller placers on the Glubokaya, Razdolnaya, Sivagli, and other
rivers, where some recent mining has occurred. The largest placer is on
the Urkima River. There are over 20 lode gold deposits in the area that
are related to hydrothermal alteration of metamorphic rock. The largest
lode deposit is at Odolgo. High-grade lode gold deposits occur near the
placer of Berikan Creek. The lode deposits were mined in the early
1900's. The Urkimin valley-type placer was discovered in 1913 on the
Urkima River, the eastern tributary of the Nyuksha River. The deposit
was mined by hand from discovery until 1947 when a low-capacity dredge
(250 liter) began operation. The total production from 1913 through 1980
is estimated as 810 kg. The placer is 18 km long, average width is 236
m, average thickness is 7.2 m, total volume of gold-bearing gravel is 32
million m3, average gold grade is 225 mg/m3, fineness of native gold is
881, and proven reserves are 7 tonnes. At present, the placer is being
mined with dredges.</p></td>
<td>V.D. Melnikov and V.V. Ratkin, written commun., 1994.</td>
<td>Russia</td>
</tr>
<tr class="even">
<td>N</td>
<td>51</td>
<td>03</td>
<td>53 55 00N</td>
<td>53.9166666666667</td>
<td>122 30 00E</td>
<td>122.5</td>
<td>Au</td>
<td></td>
<td>Verkhne-Indigirsky</td>
<td>Placer Au</td>
<td></td>
<td>Average grade of 133 mg/m3 Au. Range of 58 to 237 mg/m3 Au.</td>
<td>Production of 169 tonnes Au. Proven reserves of 3.5 tonnes Au.
Inferred reserves of 50 tonnes Au.</td>
<td></td>
<td></td>
<td>District contains more than 250 different and non-contemporaneous
placer deposits. Most deposits are flood-plain and bench placers that
occur in Holocene and interglacial deposits. Three stages of placer
formation occurred in the Oligocene-Miocene, Pliocene-Early Pleistocene,
and Late Pleistocene-Holocene. Highest-grade deposits are Pliocene and
Early Pleistocene, as at Sana, Bazovy, Dirin-Yuryak, and Elgi. These
deposits occur in intermontane depressions along major fault zones.
Placers occur on terraces 6 to 200 m above river level. Most have 0.2-20
m of overburden, but some have up to 150 m overburden. Gold-bearing beds
are 0.2-6.6 m thick and gold grades range up to 1 kg/m3 (as at Sana).
Gold nuggets up to 5 kg weight occur. Commercial placers are mostly
confined to late Pleistocene and modern fluvial deposits. These deposits
have 10 m or less overburden, are 0.5 to 15 km long, and contain
gold-bearing beds that range from 1-6.8 m thick, and have a gold
fineness of 582-907. Major deposits occur at Promezhutochny Creek,
Tuora-Tas Creek, Khangalas Creek, and Kurun-Agalyk Creek. Promezhutochny
Creek deposit consists of a buried placer deposit that occurs in Neogene
to early Pleistocene gravel. Thickness of overlying alluvial, colluvial,
and glacial deposits varies from 50 to 140 m, and averages 63 m thick.
Gold grade is 8.6 g/m3. The gold-bearing bed is 3.28 km long and
averages 62.8 m thick. The majority of the gold (80%) occurs in the
bedrock eluvium. Large gold particles comprise less than 10%; and
fineness is 840-863% with an average of 849. Gold is associated with
arsenopyrite, pyrite, anatase, and garnet. Tuora-Tas Creek flood-plain
gold placer is 10 km long and occurs in a broad valley with multiple
well-formed terraces. The gold-bearing bed is about 1.5 m thick, gold
fineness is 798, and gold particles are about 4 mm in size. Khangalas
Creek deposit consists of flood-plain and bench placers that range up to
3 km long and 150 m thick. Some individual paystreaks are 180-1,000 m
long, 0.4-3 m thick, and have 0.4 to 6 m of overburden. Gold fineness is
850. Bedrock sources of are gold-quartz veins of the Khangalas deposit.
Kurun-Agalyk valley placer is 5,500 m long and 20-150 m thick. The
gold-bearing bed is 0.2-3.6 m thick, with 2-3 m thick overburden. Gold
fineness is 856-891 and gold particles are 0.5-8 mm in size.</td>
<td>E.I. Belousov and V.D. Melnikov, written commun., 1979; B.Y. Grezin
and V.S. Borodin, written commun., 1982.</td>
<td>Russia</td>
</tr>
<tr class="odd">
<td>N</td>
<td>51</td>
<td>04</td>
<td>53 30 00N</td>
<td>53.5</td>
<td>125 30 00E</td>
<td>125.5</td>
<td>Au</td>
<td></td>
<td>Gonzhinsky (Gonzha)</td>
<td>Placer Au</td>
<td></td>
<td></td>
<td>Production of 48 tonnes Au. Proven reserves of 8 tonnes Au. Inferred
resources 66 tonnes Au.</td>
<td></td>
<td></td>
<td><p>Occurs in the western part of the Burea superterrane. Area is
underlain mainly by Precambrian metamorphic rock. The largest
gold-bearing deposits of the district (Pokrovskoe, Pioneer, Borgulikan,
Burinda, and Kulikan) are interpreted as being derived from Early
Cretaceous volcanic overlap assemblages.</p>
<p>Osezhinsky subdistrict is underlain by the Late Jurassic and Early
Cretaceous clastic trough. The largest placer is along the Bolshoi
Burgali River (the Alma-Burgali subdistrict) that has been mined
intermittently since 1890 with a total of production of 1.7 tonnes gold.
The placer is 9 km long, averages 250 m wide, and the alluvium is 4-5 m
thick. Gold-bearing strata occur in the lower part of alluvium and are
1.6 m thick. Gold is fine (0.3-0.4 mm) and poorly rounded. The placer is
being mined again after additional exploration.</p>
<p>Tygda-Ulundy gold-bearing subdistrict occurs in a hilly area in the
NW part of the Cenozoic Amur-Zeiya Basin. The area contains wide river
valleys with gentle slopes that grade into drainage divides. Topographic
relief is commonly 20 to 50 m, rarely 100 m, with the highest relief
being 340 to 360 m. The Ulunginsky placer is largest in the subdistrict.
The Ulunginsky placer deposit occurs in the valley of the middle part of
Bolshoi Ulunga Creek. The first prospect (Pioneer) was discovered in
1911. Mining operations began in 1915 and are occurring. The Aprelsky
prospect, containing both just-subsurface and also deep-seated placer
material, was discovered in 1937. The stratigraphic section (from top to
bottom) consists of: 0-3 m of yellow viscous clay and ooze; 3-7 m of
dark-brown compact ooze; a first gold-bearing bed (5-7 m below the
surface); 7-12 m of false bedrock consisting of angular pebbles derived
from granodiorite, decomposed to varied-color clay; and a second
gold-bearing bed (5 to 7 m) consisting of coarse grained gray sand with
poorly-rounded quartz pebbles. Granite boulders up to 40 cm occur
locally. About 75% of gold is irregular in shape and less that 0.25 mm
comprises about 75%. Gold from 0.5 to 2 mm diameter is of tabular shape
and very light in color. Proven reserves of the deep-seated placer are
186 kg, and inferred reserves are 500 kg. The placer is 10 km long,
average thickness of the gold-bearing bed is 1.3 m, and average
thickness of the pit layer is up to 20 m. Gold content varies from 641
to 1419 mg/m3. Gold is 0.25 to 2.0 mm with fineness of 800.</p></td>
<td>V.D. Melnikov and V.V. Ratkin, written commun., 1994.</td>
<td>Russia</td>
</tr>
<tr class="even">
<td>N</td>
<td>51</td>
<td>05</td>
<td>52 37 00N</td>
<td>52.6166666666667</td>
<td>121 40 00E</td>
<td>121.666666666667</td>
<td>Au</td>
<td></td>
<td>Mohe</td>
<td>Placer Au</td>
<td>Large</td>
<td>Grade rangefrom 0.1-9 g/m3 Au.</td>
<td>Production of 125 tonnes Au from 1970-1995.</td>
<td>856-897</td>
<td></td>
<td>Mining began in 1860 and in the past 130 years, totally 300 tonnes
Au has been produced (including district N51-02). The area covers 25,000
sq.km. and exhibits a glacial geomorphogical landscape. District occurs
along second to fourth order branches of the Argun and Heilongjiang
Rivers. Placers are classified as allurial-slope-proluvial valley
channel, allurial-slope-proluvial valley flat, and valley terrace types
that formed in Late Pleistocene and Holocene. The Holocene placers are
the most economic. Placer Au is related to the ancient placer in
Jurassic conglomerate, and to Au quartz veins in metamorphic rock and in
Paleozoic granite and Mesozoic pyroclastic rock. The Fulaoshan Placer Au
is most representative with ore bodies that dip gently along the river
channel. The size of Au grains is 0.1-0.5mm, even up to 1.0-1.5cm.</td>
<td>Lu Yingjie and others,1988; Chen Jiming and others, 1997.</td>
<td>China</td>
</tr>
<tr class="odd">
<td>N</td>
<td>52</td>
<td>01</td>
<td>54 55 00N</td>
<td>54.9166666666667</td>
<td>131 05 00E</td>
<td>131.083333333333</td>
<td>Au</td>
<td></td>
<td>Verkhnezeisk</td>
<td>Placer Au</td>
<td></td>
<td></td>
<td>Production of 24 tonnes Au. Proven reserves of 6 tonnes Au. Inferred
reserves 76 tonnes Au.</td>
<td></td>
<td></td>
<td><p>Occurs in the eastern part of the Nora-Sukhotin terrane. The
Mesozoic Mulmugin, Toksky, and Okonon plutons underlie over half of the
district, and the rest of the district is underlain by nearly equal
amounts of Early Archean metamorphic rock and Precambrian igneous
rock.</p>
<p>District consists of the Sugdzhar, Verkhnetok, Kupuri-Maisky, and
Arginsky subdistricts. Sugdzhar subdistrict occurs near the giant
Malmugin and Okonon granitoid plutons.</p>
<p>Most lode and placer deposits of the Sugdzhar subdistrict occur
within the Sivakan-Toksky block of metamorphic rock. About 20 lode
occurrences occur and are related to a long, wide (up to 7 km) shear
zone that cuts zones of schistose rock and retrograde metamorphic rock
that contain disseminated sulfides. Gold occurs in small quartz,
quartz-pyrite, quartz-epidote, and quartz-feldspar veins and veinlets,
in altered gabbro-amphibolite, and in gneisses containing quartz-filled
fractures. Most commonly, gold has a fineness of 720 to 830. Gold grains
are angular, intergrown with quartz (up to 2.5 wt.%), and are small
(normally less than 1 mm). Lode sources for gold are interpreted as
forming during Late Jurassic accretion; lode deposits occur in the areas
of intense shearing and retrograde metamorphism.</p>
<p>Verkhnetok subdistrict occurs between the Toksky and Okonon granitic
plutons. Late Archean metamorphic rock and mafic granitic rock
predominate. Estimated placer potential of the Verkhnetok subdistrict is
6 tonnes gold.</p>
<p>Kupuri-Maisky placer subdistrict occurs in the eastern Okonon pluton
in the valley of the headwaters of the Kupuri and Maai Udsky Rivers.
Archean metamorphic rock and gabbro-amphibolite predominate, and
granodiorite and diorite are subordinate.</p></td>
<td>Neronsky and Dobraya, 1976, V.D. Melnikov, written commun.,
1979.</td>
<td>Russia</td>
</tr>
<tr class="even">
<td>N</td>
<td>52</td>
<td>02a</td>
<td>54 40 00N</td>
<td>54.6666666666667</td>
<td>126 40 00E</td>
<td>126.666666666667</td>
<td>Au</td>
<td></td>
<td>Dambuki-Part A</td>
<td>Placer Au</td>
<td></td>
<td></td>
<td>Production of 185 tonnes Au. Proven reserves of 56 tonnes Au.
Inferred reserves of 88 tonnes Au.</td>
<td></td>
<td></td>
<td>District is well defined. Internal division is difficult because
gold occurs throughout. Seven tentative subdistricts are distinguished:
Mogoktak-Talginsky, Ilikan-Unakhinsky, Kokhaniisky,
Zolotogorsko-Uspensky, Dzhalta-Uldegitsky, Ugan-Mogotsky, and
Zhurbansky. The shallow Khugdersky placer and the deep Petrovsky and
Yasnopolyansky placers are described as examples. The lode sources for
the Khugdersky placer deposit are the Zolotaya Gora deposit and
retrograde metamorphic Au lode deposits. The deposit is 15.6 km long,
averages 189 m wide and 4.0 m thick, and has an average gold grade of
285 mg/m3. Fineness of gold is 940. The bedrock consists of metamorphic
rock (amphibolite, gneiss, gneissic granite, and diapthorite). Loose
sediment consists of 41% pebbles (more than 5 mm), 31% gravel (1-5 mm),
21% sand (less than 1.0 mm), and 3% ooze and clay. Gold is fine- and
medium-grained: 1.2% is up to 0.2mm, 50.6% is 0.21-0.63 mm, 7.2% is
0.64-2.5mm, and 1% is greater than 2.5 mm. Gold grains are tabular and
bright yellow, locally with a reddish tint. More than 8 tonnes of gold
is mined. Nuggets up to 18 kg were recovered. Heavy-mineral concentrates
contain scheelite, zircon, rutile, sphene, anatase, ilmenite, monazite,
andalusite, kyanite, molybdenite, apatite, epidote, garnet, pyrite,
amphibole, and pyroxene.</td>
<td>Anert, 1928; V.D. Melnikov and others, written commun., 1989.</td>
<td>Russia</td>
</tr>
<tr class="odd">
<td>N</td>
<td>52</td>
<td>02b</td>
<td>54 40 00N</td>
<td>54.6666666666667</td>
<td>126 40 00E</td>
<td>126.666666666667</td>
<td>Au</td>
<td></td>
<td>Dambuki-Part B</td>
<td>Placer Au</td>
<td></td>
<td></td>
<td>Production of 185 tonnes Au. Proven reserves of 56 tonnes Au.
Inferred reserves of 88 tonnes Au.</td>
<td></td>
<td></td>
<td>Petrovsky placer deposit occurs in a saddle on the Tukuringra Ridge.
The placer was discovered in 1897 and has been mined since 1898. It does
not coincide with a modern river system. Major accumulations of
unconsolidated Cenozoic sediments occur in a small, elongated
NS-trending basin. The slopes of the basin are mostly gentle, with
well-preserved piedmonts and wide erosional terraces, corresponding to
ancient piedmonts with elevations of 700 to 750 m. The floor and slopes
of the basin consist mostly of gneiss and amphibolite with Early Archean
marble lenses. The basin floor is rather wide (about 500 m and
indulated, with local depressions ranging from 5-10 m and 60-100 m
wide). Unconsolidated sediments are 60 m thick. Bedrock exhibits a thick
weathering crust consisting of a layer 1-3 m thick of angular
pebble-sized fragments that occurs almost everywhere at the base of the
sequence of gold-bearing gravel. Unconsolidated material is mainly sandy
pebble gravel to pebble sand, with beds and lenses of gravelly mud and
peat, muddy sand, and compact clay. The largest and most poorly-rounded
clasts are concentrated in the deepest part of the basin, its center.
There are several gold-bearing beds in the section, although the richest
gold deposits occur in the lowermost gravel beds and in the bedrock
weathering crust. Grains less than 1.0 mm form 82-90% of the gold of
this ancient placer. Some nuggets occur, mostly 2 to 12 kg and rarely up
to 100 kg. Fineness of gold is 950-962. An alluvial origin is
interpreted for the sediments of the Petrovsky placer. Anert (1928)
proposed initially an origin as an eluvium placer that was redeposited
virtually in situ. The placer is presently being mined as a small-scale
operation, producing 30 to 60 tonnes gold per year. A total of 4-5
tonnes gold have been produced. Proven reserve is 1 tonne Au; inferred
reserves are 2-3 tonnes Au.</td>
<td>Anert, 1928; V.D. Melnikov and others, written commun., 1989.</td>
<td>Russia</td>
</tr>
<tr class="even">
<td>N</td>
<td>52</td>
<td>03</td>
<td>53 50 00N</td>
<td>53.8333333333333</td>
<td>130 00 00E</td>
<td>130</td>
<td>Au</td>
<td></td>
<td>Dzhagdy</td>
<td>Placer Au</td>
<td></td>
<td></td>
<td>Production of 20 tonnes Au. Proven reserve of 2 tonnes Au. Inferred
reserve 51 tonnes Au.</td>
<td></td>
<td></td>
<td>Occurs in the Tukurigra-Dzhagdi terrane and is subdiviided into the
elongate, EW-trending Un'ya-Bomsky subdistrict that contains most of the
placer gold deposits, and a group of subdistricts to the south
(Verkhnedepsky, Tuksinsky, and Egorsky). Placer and lode deposits
clearly restricted to the EW-trending Un'insky thrust fault. Streams are
rapid and steep and occur in canyons. Un'ya Creek has the widest flood
plain (300-450 m) and the the valley of the Bom Creek is steep. Valleys
of tributaries (rapids) of the Bom Creek are steeper. Yasnaya Polyana
placer deposit occurs in the Yasnaya Polyana basin. The upper level of
ancient alluvium was mined in the 1920s. The Yasnaya Polyana basin is 14
km long and 0.6-2 km wide. The basin occurs in a fault zone between
Early Archean Dambuki and Late Archean Ilikansky blocks. The basin is
filled with sand, pebble gravel, and clay. Clasts are well-rounded and
consist of granite, gneiss, and quartzite, with less common amphibolite
and volcanic rock (rhyolite, andesite, and dacite). The placer occurs at
the thalweg of a northwest-trending paleovalley. Absolute heights
(elevations over the sea level) range from 462.7 m at the western part
of the deposit to 403.5 m at its eastern part. The gold-bearing beds are
predominantly gravel and pebble with larger clasts. Coarse sand makes up
20%, and clay 15%. The thickness of the gold-bearing bed ranges from 1
to 17.6 m, gold grade varies from colors to 17,966 mg/m3. Gold grains
occur 0.4-0.8 m into the bedrock. Gold grains are either small (less
than 0.1 mm) of irregular dendritic shape, or are larger, tabular,
poorly-rounded grains. Scarce intergrowths of gold with other minerals
(quartz, pyrite commonly with galena) generally occur as small grains
(less than 0.16 mm). Gold is bright yellow, about 15% of grains are
light yellow (straw-like color). These grains are rounded,
spindle-shaped. The fineness of native gold is 967. The bedrock consists
of granite, Paleoproterozoic granodiorite and gneiss, and Archean
amphibolite. Born Creek placers are largely concentrated in the first
flood plain terrace that is 40-45 m high and 400-450 m wide. The
deposits are about 5 m thick and gold-bearing throughout the whole
length of the creek. Gold distribution is extremely irregular. Gold
occurs locally on the floor of the creek and in tiny fractures in the
greenschist bedrock. Gold grains are coarse and nuggets up to 400 kg g
occur. Un'ya Creek deposit contains both terrace- and valley-type
placers. The valley placer part is 20 to 120 m wide. Valley alluvium is
2.5 to 6.0 m thick. The gold-bearing bed consisting of gravel and pebble
near the bedrock is 0.2 to 0.6 m thick. Terrace placers of Un'ya Creek
are also mainly related to the first flood plain terrace, that is 15-20
m high. Terrace alluvium ranges from 6 to 25 m thick. Gold distribution
is irregular. Gold is coarse and poorly rounded. Quartz fragments in
some places contain visible gold and scheelite.</td>
<td>V.D. Melnikov and others, written commun., 1985.</td>
<td>Russia</td>
</tr>
<tr class="odd">
<td>N</td>
<td>52</td>
<td>04a</td>
<td>52 50 00N</td>
<td>52.8333333333333</td>
<td>128 50 00E</td>
<td>128.833333333333</td>
<td>Au</td>
<td></td>
<td>Zeiya-Selemdzha-Part A</td>
<td>Placer Au</td>
<td></td>
<td></td>
<td>Production of 111 tonnes Au. Proven reserves of 29 tonnes Au.
Inferred resources 101 tonnes Au.</td>
<td></td>
<td></td>
<td><p>District is underlain by Early Cretaceous volcanic rock that
mostly overlie the Nora-Sukhotin terrane. District is divided into the
Umlekan, Yasnensky, Oktyabrsky, Sokhatiny, Chagoyan, and Nizhneselemdzha
subdistricts. The Zeiya-Selemdzha placer gold district has the largest
gold reserves in the the Amur region.</p>
<p>Umlekan subdistrict covers an area of about 3,000 km2 in the valley
of the Umlekan and Nemogin Rivers, and in the valley of the Zeiya River
from the mouth of the Chalbachi Creek to the mouth of the Bugo Creek.
The first discovery was a rich placer on a bar in the Zeiya River near
the mouth of the Bugo Creek. The subdistrict occurs in an Early
Cretaceous caldera. Numerous lode occurrences are in the subdistrict and
consist of quartz veins in hydrothermally altered volcanic rock and in
granodiorite that intrudes Jurassic sandstone. About 20 small placers
occur in the subdistrict. Some are exhausted; others were only explored
(Umlekan and Algachan Rivers). Gold in placers is of variable size and
shape, often in intergrowths with quartz. Fineness is 750-850. The
sources for shallow-seated placers of small creeks are gold-bearing,
hydrothermally-altered volcanic rock.</p>
<p>Yasnensky subdistrict occurs in the basin of the Yasny Creek, the
adjacent valley of the the Dep River, and the headwaters of the Gar 1
and Gar 2 Rivers. Most placers are occur in early Quaternary deposits.
More than 25 placers occur in the subdistrict, most are exhausted.
Extremely interesting data were obtained from a prospecting trench
crossing the valley of the Gar 2 River at the mouth of the Karakatitsa
Creek. This trench contains a displaced weathering crust of greenstone
rock, and the 665 nuggets recovered from this trench differ sharply from
gold of the placer by having higher fineness values. The lode source is
unknown.</p></td>
<td>V. Lozhnikov and others, written commun., 1984; V.D. Melnikov and
others, written commun., 1985.</td>
<td>Russia</td>
</tr>
<tr class="even">
<td>N</td>
<td>52</td>
<td>04b</td>
<td>52 50 00N</td>
<td>52.8333333333333</td>
<td>128 50 00E</td>
<td>128.833333333333</td>
<td>Au</td>
<td></td>
<td>Zeiya-Selemdzha-Part B</td>
<td>Placer Au</td>
<td></td>
<td></td>
<td>Production of 111 tonnes Au. Proven reserves of 29 tonnes Au.
Inferred resources 101 tonnes Au.</td>
<td></td>
<td></td>
<td>The largest placer of the Yasnensky subdistrict is the Yasny Creek
placer, discovered in 1934. It was mined from 1935 to 1937. More
recently, the deposit was mined using a dredge and exhausted. The
bedrock consists of crushed extrusive rock, with less common sandstone
and siltstone. Gold-bearing gravel directly overlies bedrock. Gold
distribution is uneven. Gold content decreases sharply to colors as
distance above bedrock increases. Gold grain shapes are irregular and
rounded. Intergrowths with quartz or quartz and tourmaline are common.
Gold fineness is 900, gold grains are coarse (2-4 mm), and nuggets of
30-60 g are common. Nuggets locally locally reach 100 g. The
gold-bearing bed is overlain by gold-bearing ooze and clay (0.5-4.0 m),
and less common sandy-clay deposits 0.3-1.7 m thick. The section is
covered by a bed of soil 0.3-0.5 m thick.</td>
<td>V. Lozhnikov and others, written commun., 1984; V.D. Melnikov and
others, written commun., 1985.</td>
<td>Russia</td>
</tr>
<tr class="odd">
<td>N</td>
<td>52</td>
<td>04c</td>
<td>52 50 00N</td>
<td>52.8333333333333</td>
<td>128 50 00E</td>
<td>128.833333333333</td>
<td>Au</td>
<td></td>
<td>Zeiya-Selemdzha-Part C</td>
<td>Placer Au</td>
<td></td>
<td></td>
<td>Production of 111 tonnes Au. Proven reserves of 29 tonnes Au.
Inferred resources 101 tonnes Au.</td>
<td></td>
<td></td>
<td><p>Sokhatiny gold-bearing subdistrict occurs in the valley of the
Sokhatiny River and headwaters of the Mamyn River (Orlovka, Levy and
Pravy Mamyn Creeks). The placers of the Sokhatiny River were discovered
in 1942, and have been mined from 1948 through the present time. Bedrock
consists of early Paleozoic granitic rock cutting Proterozoic to
Cambrian deposits, as well as small Early Cretaceous intrusions and
numerous dikes. Only three lode occurrences occur in the subdistrict,
consisting of quartz-tourmaline breccia zones with sulfides and altered
quartz-sericite rock. About 30 placers have been discovered; many of
them are mined out. The valley of the Adamikha River is being
explored.</p>
<p>Oktyabrsky subdistrict occurs in the valley of the Dzheltulak River
and the headwaters of Inkan, Elna, and Bolshoy Kalakhta Creeks. Gold was
discovered in 1937 in the Dzheltulak 1 and Dzheltulak 2 Rivers, and in a
very rich placer in Sandunovsky Creek, a tributary of the Dzheltulak 1
River. Numerous placers were later discovered and prospected within the
subdistrict, that are still being mined using dredges. The subdistrict
is underlain mainly by early Paleozoic granite with fragments of Late
Proterozoic to Early Cambrian schist and marble, Silurian conglomerate,
sandstone, siltstone, and Devonian clastic carbonate rock. Numerous lode
gold occurrences are in quartz-carbonate and calcedony veins. Small
gold-bearing skarn bodies in limestone are less common. Most gold
placers are hosted in early to middle Quaternary sediments. Almost all
placers are alluvial, either valley or terrace, locally mixed. Eluvium
and talus placers such as Nagornaya and Morennaya are uncommon. Modern
and ancient placers occur separately: modern ones occur below the talweg
of the valley (or close to it) at a depth of 3-6 m. Old placers are not
related to the modern valley floor and much deeper (5 to 15 m). Locally
old and modern placers occur one above the other and are separated by a
layer of barren sediment. In some valleys, old placers are eroded either
completely or partly, forming modern placers. The bedrock is generally
heavily weathered granite that forms angular pebbles and clay. The
gold-bearing bed of old placers consists of heavily eroded pebbles with
clay patches of different shades and pebbly sandy-clay deposits. Gold
generally occurs in the middle part of beds. Native gold fineness is
commonly high, up to 950. Large nuggets up to 500 grams occur locally as
at the headwaters of the Kalakhta River. Gold in placers is associated
with scheelite and cinnabar, and less commonly with galena. Modern
placers have lower gold grades, occur in the flood valley alluvium, and
consist of clay, ooze, and sand with pebbles. Native gold fineness in
modern alluvium placers (up to 885) is locally significantly lower than
in older placers. The lower fineness results from being derived directly
from lode sources, rather than from erosion and reconcentration Chagoyan
gold-bearing subdistrict occurs in the southern area in the Zeyia River
valley from the mouth of the Tygad River to the mouth of the Gramatukha
River, including tributaries. Placers have been mined since 1893. Lode
gold occurrences (seen in talus) in the valley of the Malyutka River
contain fragments of veined quartz with visible gold. A prospecting
drill hole on the Chagoyan polymetallic deposit has high gold grades at
depths of 29-32 m.</p>
<p>Gold placers within the Chagoyan subdistrict occur either in bars or
river bottom. Gold is coarse and of different shapes. In the headwaters
of Maly Chukan and Chagoyan Creeks, nuggets up to 140 g occur as
intergrowths with quartz. Native gold fineness is 675-911.</p></td>
<td>V. Lozhnikov and others, written commun., 1984; V.D. Melnikov and
others, written commun., 1985.</td>
<td>Russia</td>
</tr>
<tr class="even">
<td>N</td>
<td>53</td>
<td>01</td>
<td>53 00 00N</td>
<td>53</td>
<td>132 45 00E</td>
<td>132.75</td>
<td>Au</td>
<td></td>
<td>Verkhne-Yansky</td>
<td>Placer Au</td>
<td></td>
<td></td>
<td>Production of 137 tonnes Au. Proven reserves of 29.0 tonnes Au.
Inferred reserves of 60.0 tonnes Au.</td>
<td></td>
<td></td>
<td>District contains about 60 cassiterite placer occurrences that form
groups of three to ten placer deposits; each group is closely related to
their bedrock sources. Main types are eluvial-slope and ravine placer
deposits that range up to some km long and about 100 meters wide.
Thickness of the payable bed ranges up to 15-20 m and sometimes larger.
Cassiterite is generally fine- to sometimes coarse-grained. Buried
placers also occur. A major deposit occurs at Kerbeng Creek. Kerbeng
Creek deposit consists of three cassiterite-bearing beds from 4-15 m
thick. The paystreak is 100-620 m wide and occurs under 1.7-24 m of
overburden. Grades are 330-2,000 g/m3 cassiteriete and 45-81 g/m3
wolframite. Bedrock sources are Sn quartz veins and stockworks of the
Kuturuk Mountain.</td>
<td>V.D. Melnikov and others, written commun., 1985 ; V.D. Melnikov and
V.D. Polevanov, written commun., 1990.</td>
<td>Russia</td>
</tr>
<tr class="odd">
<td>N</td>
<td>53</td>
<td>02</td>
<td>52 13 50N</td>
<td>52.2305555555556</td>
<td>133 52 59E</td>
<td>133.883055555556</td>
<td>Au</td>
<td></td>
<td>Sofiiskoe</td>
<td>Placer Au</td>
<td>Medium</td>
<td></td>
<td>Deposits are mined out.</td>
<td>750-800</td>
<td></td>
<td>Occurs in stream deposits in the upper reaches of the Niman River (a
tributary of the Burea River). Total length of placers is approximately
30 km. Fine- and medium-grained gold occurs irregularly. Gold fineness
is 750-800. Gold is derived from greenschist facies rock of the Sofiisky
metamorphic dome that contain streaks, veins, and lenses of gold-bearing
quartz. Gold-bearing tributaries drain small veinlet deposits. Placer
deposits are exhausted.</td>
<td>N.V. Ognyanov in Nokleberg and others, 1997.</td>
<td>Russia</td>
</tr>
<tr class="even">
<td>N</td>
<td>53</td>
<td>03</td>
<td>52 24 00N</td>
<td>52.4</td>
<td>135 44 28E</td>
<td>135.741111111111</td>
<td>Au</td>
<td></td>
<td>Kerbi</td>
<td>Placer Au</td>
<td>Small</td>
<td></td>
<td></td>
<td>800-850</td>
<td></td>
<td>Occurs in Kerbi River valley numerous tributaries. Total length of
gold-bearing beds is approximately 35 km. Gold is fine- and
medium-grained with fineness of 800-850. Bedrock is Jurassic black shale
that is metamorphosed to greenschist facies with thin scattered streaks
of gold-bearing quartz.</td>
<td>N.V. Ognyanov in Nokleberg and others, 1997.</td>
<td>Russia</td>
</tr>
<tr class="odd">
<td>N</td>
<td>54</td>
<td>01</td>
<td>53 51 32N</td>
<td>53.8588888888889</td>
<td>139 49 27E</td>
<td>139.824166666667</td>
<td>Au</td>
<td></td>
<td>Ulskoe</td>
<td>Placer Au</td>
<td>Small</td>
<td></td>
<td></td>
<td>850-900</td>
<td></td>
<td>District contains stream and bench placers of the Ul Orelsky River
and tributaries. Total length of placers along the Ul Orelsky River and
tributaries is approximately 15 km. Gold is associated with vein quartz
and fineness is 850-900. Local bedrock consists of Early Cretaceous
siltstone, sandstone, and Late Cretaceous volcanic rock. Deposit derived
from the Mnogovershinnoe lode gold deposit.</td>
<td>N.V. Ognyanov in Nokleberg and others, 1997.</td>
<td>Russia</td>
</tr>
<tr class="even">
<td>N</td>
<td>54</td>
<td>02</td>
<td>53 34 49N</td>
<td>53.5802777777778</td>
<td>140 21 18E</td>
<td>140.355</td>
<td>Au</td>
<td></td>
<td>Kolchanskoe</td>
<td>Placer Au</td>
<td>Small</td>
<td></td>
<td></td>
<td>500-600</td>
<td></td>
<td>District contains low-grade stream placers along the Kolchan River
and tributaries with a total length of approximately 10 km. Gold is
fine-grained, and fineness is 500 to 600. A few nuggets occur, ranging
up to 10-20 g. Gold is associated with quartz and adularia. Local
bedrock consists of volcanic rock and hydrothermally altered siliceous
rock. Placer deposits are derived mainly from the Belogorsk lode deposit
that consists of late Paleogene gold-bearing altered siliceous rock with
quartz-adularia alteration. Deposits are mined out.</td>
<td>N.V. Ognyanov in Nokleberg and others, 1997.</td>
<td>Russia</td>
</tr>
<tr class="odd">
<td>N</td>
<td>54</td>
<td>03</td>
<td>53 02 26N</td>
<td>53.0405555555556</td>
<td>138 46 04E</td>
<td>138.767777777778</td>
<td>Au</td>
<td></td>
<td>Kherpuchinskoe</td>
<td>Placer Au</td>
<td>Medium</td>
<td></td>
<td></td>
<td>700-850</td>
<td></td>
<td>District contains stream deposits along the Kherpuchi River and
tributaries of the Somni spring (a tributary of the Amgun River). Placer
deposits occur both in main and branch valleys along a distance of over
25 km. Gold is fine- or medium-sized, and high-grade. Vein quartz occurs
in the gold-bearing sand. Gold is derived from small quartz veins and
veinlets that contain gold and arsenic sulfides. Local bedrock consists
of Early Cretaceous sandstone and siltstone.</td>
<td>N.V. Ognyanov in Nokleberg and others, 1997.</td>
<td>Russia</td>
</tr>
<tr class="even">
<td>N</td>
<td>54</td>
<td>04</td>
<td>52 36 45N</td>
<td>52.6125</td>
<td>139 28 35E</td>
<td>139.476388888889</td>
<td>Au</td>
<td></td>
<td>Oktyabrskoe</td>
<td>Placer Au</td>
<td>Small</td>
<td></td>
<td></td>
<td>800-850</td>
<td></td>
<td>District contains alluvial-colluvial placers that the valley and
slopes of the Pochel River (a tributary of the Amgun' River). Gold is
concentrated largely in a weathering crust developed in a gold-bearing,
mid-Cretaceous tonalite that contains quartz streaks with As and Pb
sulfides. Rock-forming minerals from the tonalite and veined quartz are
abundant in gold-bearing sands. Gold is fine- and medium-grained.</td>
<td>N.V. Ognyanov in Nokleberg and others, 1997.</td>
<td>Russia</td>
</tr>
<tr class="odd">
<td>N</td>
<td>54</td>
<td>05</td>
<td>54 05 51N</td>
<td>54.0975</td>
<td>142 55 26E</td>
<td>142.923888888889</td>
<td>Au</td>
<td></td>
<td>Schmidtovskoe</td>
<td>Placer Au</td>
<td>Small</td>
<td></td>
<td></td>
<td>800-900</td>
<td></td>
<td>District contains small placers, 30 to 10 m wide and up to 1000 m
long. Gold occurs throughout a 3 to 4 m thick section of modern
alluvium, although a 1.2 to 1.4 m thick zone near bedrock is the
richest. Alluvium consists of ultramafic and mafic rock that are altered
to chlorite, zeolite, and albite. Heavy-mineral concentrates contain
chromite, magnetite, pyrite, and siderite. Gold grains are normally
larger than 0.5 mm. Some gold forms intergrowths with albite and
magnetite. The bedrock source of the placer deposits is gold-bearing
zeolite-epidote-prehnite-chlorite and albite-pyrite-chlorite rock that
occurs at the contact with serpentinized ultramafic rock and propylitic
altered gabbro. Source rock contain up to 2 g/t Au.</td>
<td>V.D. Sidorenko, 1977.</td>
<td>Russia</td>
</tr>
<tr class="even">
<td>O</td>
<td>51</td>
<td>01</td>
<td>56 28 00N</td>
<td>56.4666666666667</td>
<td>122 01 00E</td>
<td>122.016666666667</td>
<td>Au</td>
<td></td>
<td>Nizhnenyukzinsky district</td>
<td>Placer Au</td>
<td></td>
<td></td>
<td>Inferred reserves of 35 tonnes Au.</td>
<td></td>
<td></td>
<td>District is the largest in the Russian Far East and occurs north of
the Mesozoic Chilchinsky granitic pluton that intrudes Early and Late
Archean metamorphic rock. Pluton consists of anorthosite (Kalar pluton),
syenite (Tassky pluton), and granite (Sedolchinsky and Cheremkhalaksky
plutons). In the northern part of the district, zones of retrograde
metamorphism occur along the Stanovoi and Yuzhnoaldan regional faults
that occur between the Aldan shield (Siberian Craton) and Nora-Sukhotin
terrane. Only a few placers occur. The total potential (mined + proven
reserves + inferred reserves) comprises 2% of the total potential of the
Amur Region. Darynmakitsky placer deposit, the best-studied deposit in
the district, was discovered in 1929 and was mined during the 1930s.
Gold occurs for a distance of 10 km. The placer averages 60 m wide,
alluvium ranges from 4 to 6 m thick, and gold-bearing gravel occurs in
the lower 2 m of the alluvium. Average grade is 450 mg/m3 Au. The
richest part of the placer occurs near bedrock and consists of eluvium,
with gold-bearing sand filling fractures. Lode sources for the placer
are presumably quartz veins and zones of cataclastic and weakly altered
sulfide-bearing rock, both closely related to the Stanovoi fault
zone.</td>
<td>V.D. Melnikov, written commun., 1979.</td>
<td>Russia</td>
</tr>
<tr class="odd">
<td>O</td>
<td>53</td>
<td>01</td>
<td>58 37 01N</td>
<td>58.6169444444444</td>
<td>137 11 02E</td>
<td>137.183888888889</td>
<td>Au</td>
<td></td>
<td>Kurun-Uryakh</td>
<td>Placer Au</td>
<td></td>
<td>Average grade of 3.2-4.5 g/m3 Au.</td>
<td>Production of about 12 tonnes Au.</td>
<td></td>
<td></td>
<td>Consists of a buried placer that is 5 km long and 0.2-0.4 km wide.
Depth of overburden ranges from 5-30 m. Gold-bearing bed is 0.2 m thick,
and grade is 3.2-4.5 g/m3. Interpreted as derived from the Malyutka
gold-quartz deposit. District includes several small deposits.</td>
<td>P.P. Smirnov, written commun., 1961; N.L. Kobtseva, written commun.,
1988.</td>
<td>Russia</td>
</tr>
<tr class="even">
<td>O</td>
<td>53</td>
<td>02</td>
<td>57 36 14N</td>
<td>57.6038888888889</td>
<td>134 38 15E</td>
<td>134.6375</td>
<td>PGE</td>
<td>Au</td>
<td>Kondyor</td>
<td>Placer PGE</td>
<td>Major</td>
<td></td>
<td>Production of 3 tonnes PGE in 1993. Second largest placer PGE
producer in Russia</td>
<td></td>
<td>Mining since about 1988</td>
<td>Consists of an alluvial placer that occurs in the north-flowing
Kondeur River valley. Richest placer occurs in a 10 km-long paystreak
that averages 100 m wide. Placer platinum occurs in 6-8 m thick fluvial
gravels on or just above bedrock. Typical platinum grains range from 0.5
mm to 1 cm in diameter. A 4.3 kg iso-ferro-platinum nugget was recovered
recently. Iso-ferro-platinum is commonly combined with chromite. Small
inclusions of Ir-Os minerals occur in larger platinum nuggets. Gold
comprises 10% of total production, and occurs in cubic crystalline form
with individual cubes up to 1 cm across. Gold contains up to 40% Cu and
up to 10% Pd. Deposit was discovered in the 1970's. Minor production
occurred in early years from small, high-grade placer pockets. Present
production is from placers near the head of the drainage. Kondyor placer
deposits are derived from lode deposits in the Kondyor zoned
mafic-ultramafic complex.</td>
<td>V. Molchanov and V. Sapin, written commun., 1993.</td>
<td>Russia</td>
</tr>
<tr class="odd">
<td>O</td>
<td>53</td>
<td>03</td>
<td>56 27 00N</td>
<td>56.45</td>
<td>132 54 00E</td>
<td>132.9</td>
<td>Ti</td>
<td>REE</td>
<td>Sash-Yular</td>
<td>Placer Ti</td>
<td></td>
<td>Average grade of 8.2 kg/m3 monazite, 15.6 kg/m3 ilmenite, 5 kg/m3
rutile.</td>
<td>Reserves of 82,000 tonnes monazite with 820 tonnes Th, 19,200
tonhnes REE, and 88,000 tonnes Zr. Reserves of 849,000 tonnes
ilmenite.</td>
<td></td>
<td></td>
<td>No summary provided.</td>
<td>Onikhimovskiy and Belomestnykh, 1996.</td>
<td>Russia</td>
</tr>
<tr class="even">
<td>O</td>
<td>54</td>
<td>01</td>
<td>59 44 21N</td>
<td>59.7391666666667</td>
<td>143 26 34E</td>
<td>143.442777777778</td>
<td>Au</td>
<td></td>
<td>Okhotsk</td>
<td>Placer Au</td>
<td></td>
<td>Average grade of 3 to 47 g/m Au.</td>
<td>Production of about 15 tonnes Au through 1930. Most deposits mined
out.</td>
<td>720-850</td>
<td></td>
<td>District discovered in 1829 and covers an area of about 140 sq. km.
About ten placer deposits occur in the district. Nearly all are
exhausted, and a few are mined at the present. Placer deposits occur in
valleys; some are buried. Gold-bearing beds range from 0.12 to 14 m
thick and up to 2,000 m long. Gold nuggets to 1 kg occur. Bedrock
sources for placer deposits are unknown. Examples of placer deposits are
at Zolotoi Creek and Raasvet Creek/Gusinka Creek. Zolotoi Creek placer
deposit is a buried placer that is 2.9 km long and averages 54 m wide.
Depth of overburden is 17 m. Two placer beds occur. The lower bed is 1.8
m thick and directly overlies a weathered crust developed on Cretaceous
rhyolite. The upper placer bed is 2.4-5.4 m thick and overlies a false
clay bedrock. Gold grade ranges from 2.9-9 g/m3. Gold is mostly
fine-grained, with an average size of 0.4 mm. Gold fineness is 717-770.
Gold nuggets are scarce but nuggets up to 129 g are recovered. Bedrock
sources are unknown. Gold production is about 2 tons. Raasvet Creek and
Gusinka Creek placer deposits are 600 m long and range from 30-100 m
wide. The gold-bearing bed is 0.2-1.8 m thick, with about 4 to 10 m of
overburden. Gold grade is 1.5-42.7 g/m3. Gold is coarse-grained. One
gold nugget with minor quartz, weighing nearly 1 kg, was found. Gold
fineness is 820-850. Bedrock sources are unknown. Production of 233 kg
gold.</td>
<td>P.P. Smirnov, written commun., 1962; N.L. Kobtseva, written commun.,
1988.</td>
<td>Russia</td>
</tr>
<tr class="odd">
<td>P</td>
<td>54</td>
<td>01</td>
<td>61 00 30N</td>
<td>61.0083333333333</td>
<td>138 08 55E</td>
<td>138.148611111111</td>
<td>Au</td>
<td></td>
<td>Allakh-Yun</td>
<td>Placer Au</td>
<td></td>
<td>Average grade of 1 to 10 g/m3 Au.</td>
<td>Production of about 23 tonnes Au between 1940 to 1964.</td>
<td>813-844</td>
<td></td>
<td>District contains about 150 placer deposits, mostly in the Allak-Yun
and Yudoma River basins. Small channel-fill placers occur in the
northern part of area. Medium-size and some large valley placers and
sparse bench placers occur in the middle part of district. Flood-plain
placer deposits and some channel-fill deposits occur in southern part of
district. Gold placers occur in interglacial deposits. Gold-bearing beds
range from 0.5 to 3 m thick. Depth of overburden ranges up to 100 m. The
highest-grade gold placers occur in the southern part of the district.
Placers range from 1 to 10 km long and up to 200 m wide. Gold nuggets to
1 kg weight occur. Bedrock sources are Au quartz vein deposits.
Individual placer deposits are at Zhar Creek, Yur-Duet, and Brindakit.
Zhar Creek placer deposit is 7 km long. Average thickness of
gold-bearing bed is 1.4 m and the overburden is 3.5 m thick. Fine gold
(particles less than 1 mm in size) comprise 87% of all gold. Five
percent of gold occurs as nuggets weighing 10 to 200 g. Bedrock source
of this placer is Au quartz veins. 2.7 tonnes gold produced between 1940
to 1964. Yur-Duet and Brindakit placer consist of several auriferous
placer zones. Largest is 10 km long and from 10-300 m wide. Gold grade
is 1-7.3 g/m3. The gold-bearing bed is 0.2-3.2 m thick, with 20-30 m
overburden. The average size gold particles is 1-2 mm, fineness 813-844.
Gold nuggets to 1,050 gm were common at the Yur placer deposit. About 20
tonnes of gold produced between 1940-1964.</td>
<td>P.P. Smirnov, written commun., 1961; V.I. Korostelev, written
commun., 1963; Trushkov, 1971; N.L. Kobtseva, written commun.,
1988.</td>
<td>Russia</td>
</tr>
<tr class="even">
<td>Q</td>
<td>52</td>
<td>01</td>
<td>65 53 47N</td>
<td>65.8963888888889</td>
<td>129 45 11E</td>
<td>129.753055555556</td>
<td>Au</td>
<td></td>
<td>Verkhoyan</td>
<td>Placer Au</td>
<td></td>
<td>Average grade of up to 15 g/m3 Au.</td>
<td></td>
<td>703-766</td>
<td></td>
<td>District contains several small valley and ravine placers. Deposits
range up to 4 km long and 50 m wide. Bench placers also occur. Placer
deposits are buried by 1-3 m of alluvium. Gold-bearing beds are less
than 2 m thick. Gold occurs irregularly in radial and ore pocket forms.
Erosion-caused truncation is minor and does not indicate a wider
occurrence of placer deposits. The Chochimbal Creek placer deposit is
typical of deposits in this district. Chochimbal deposit occurs as a
valley placer that occurs in the upper reaches of Chochimbal Creek. The
deposit is about 4 km long and 10-50 m wide. Average depth of overburden
is about 2 m. The gold-bearing bed is 0.6-3.6 m thick, averagely 1.71 m.
Gold grade ranges up to 15 g/m3. Near bedrock, gold particles are very
large (up to 10.1 mm) and gold nuggets range up to 150 g and constitute
39% of the gold. Bedrock sources are small Au quartz veins and, probable
Au polymetallic veins. The deposit is exhausted.</td>
<td>Trushkov, 1971; Ivensen and others, 1975; Yu.A. Vladimirtseva,
written commun., 1985.</td>
<td>Russia</td>
</tr>
<tr class="odd">
<td>Q</td>
<td>53</td>
<td>01</td>
<td>67 23 09N</td>
<td>67.3858333333333</td>
<td>134 11 17E</td>
<td>134.188055555556</td>
<td>Sn</td>
<td></td>
<td>Verkhnegilyui</td>
<td>Placer Sn</td>
<td></td>
<td>Ranges up to 1,169 g/m3 cassiterite.</td>
<td></td>
<td></td>
<td></td>
<td><p>District is divided into the Apsakan, Laprin, Malogilyui, and
Bryantin subdistricts. Occurs in the axial part of the Stanovoi
anticline. Gold-bearing areas within the district occur close to the
Mesozoic Tynda, Dyupkoisky, Unakhinsky, and Mulmugin plutons.</p>
<p>Apsakan subdistrict occurs in basins at the headwaters of the Verkhny
Larba, Nizhny Larba, and Sredny Larba Rivers, along the NW margin of the
Tynda pluton that intrudes Proterozoic granite and Archean metamorphic
rock. The ratio between the number of lode deposits and placer deposits
in the Apsakan subdistrict is 3:2. This is the only subdistrict in the
Verkhnegilyui district, where the number of lode deposits is greater
than the number of placers. More than 25 lode deposits occur, and all
are associated with zones of hydrothermally altered metamorphic rock.
Every placer or low-grade placer deposit overlies a lode deposit. The
Larba River placer is the largest in the subdistrict. It was discovered
in 1929, and was prospected in the 1930's and 1940's. It includes
several small creek placers with a total length of 21 km. Deposit starts
in the middle of Yanvarsky Creek, continues along the valleys of the
Khorogochikan Creek (from the mouth of the Yanvarsky Creek to the
confluence with the Sredny Larba Creek), and terminates 4 km downstream
from the mouth of Gromkachi Spring. Au content is extremely uneven.
Native gold occurs in the lowest bed of pebble deposits and in the upper
part of underlying eluvium. Terraces are not studied. Estimated reserves
are 2003 kg.</p>
<p>Laprin subdistrict occurs in predominantly Late Archean metamorphic
rock between the Mesozoic Tynda and Dyupkoisky plutons. Cretaceous rock
of the Tiptursky volcanic field occur sin the NE part of the
subdistrict. Only a small portion of the subdistrict is mined. At the
beginning of the previous century, only placers of the Khitrusha,
Maksimovka (Lapri River basin), and Bugorikty (Mogota River basin)
Rivers were mined. Placer mines are being planned for the Malinovy,
Lysovsky, Tsyganka, and Medvezhi Creeks. The largest placer in this
subdistrict, the Khitrusha valley-type deposit, occurs in the Khitrushka
Creek that is a tributary of the Lapri River. The deposit has been mined
from 1928 to 1950, and there is evidence of earlier operations
(presumably 1880-1900). About 4 km of the placer deposit are mined. The
placer averages 60 m wide and 3.4 m thick. Gold grade is 297 mg/m3 and
fineness of native gold is 900. Inferred reserves are 1200 kg
(V.D.Melnikov, written comm., 1990).</p>
<p>Malogilyui subdistrict is related to Cambrian metamorphic rock
between the Dyupkoisky granodiorite pluton and the Mesozoic Unakhinsaky
granite-granodiorite pluton. Placers of the Malogilyui subdistrict were
previously mined in valleys of the Des (Kamenisty), Olongo (Somnitelny,
Marmontovsky), and Maly Gilui (Karlovsky, Kruglovsky, and Kurnosovsky)
Rivers. The potential of the area is about 19 tonnes gold.</p>
<p>Bryantin subdistrict occurs between the Unakhinsky and Mulmugin
plutons. Au-Cu-Mo porphyry deposits occur in the area along with
numerous other lode gold deposits. Additional lode gold deposits are
associated with hydrothermally altered metamorphic rock. All known lode
deposits have related placers deposits. Total placer potential of the
subdistrict is 12 tonnes gold.</p></td>
<td>P.O. Genkin and E.A. Sinuygina, written commun., 1973; M.E.
Gorodinsky, written commun., 1991.</td>
<td>Russia</td>
</tr>
<tr class="even">
<td>Q</td>
<td>53</td>
<td>02</td>
<td>66 42 02N</td>
<td>66.7005555555556</td>
<td>137 28 59E</td>
<td>137.483055555556</td>
<td>Au</td>
<td></td>
<td>Adychan</td>
<td>Placer Au</td>
<td></td>
<td>Average grade of 0.2 to 34.4 g/m3 Au.</td>
<td></td>
<td>475 to 960</td>
<td></td>
<td>District contains more than 60 placer deposits that are mostly small
and non-commercial. Deposits include buried placers in neotectonic
depressions (as at Nadezhnoe), and high terrace and valley placers.
Deposits in depressions are Miocene to Pliocene. Modern deposits occur
on spits. Placer deposits range from 700 to 12,700 m long and 5 to 1,000
m wide. Overburden of glacial drift ranges from 0.4 to 70 m thick and
gold-bearing layers are 0.2 to 7 m thick. Gold-bearing gravels in each
district occurs as descrete paystreaks of two morphologies, highly
elongate and sub-equant. Gold sometimes occurs in rich pockets. Gold
particles range in size, and nuggets up to 580 g occur. Associated
minerals are cassiterite, wolframite, scheelite, and cerolite. Twenty
percent of placers were mined, and some are currently being worked. Lode
sources are Au quartz veins and mineralized shear zones and, less
commonly, gold-REE deposits related to granitoids. Major deposits are at
Adychanskoe, Adycha, Nadezhnoe, and Lazo. Adychanskoe deposit occurs on
the Adycha River terrace 75 to 100 m above river level. Deposit is 12.4
km long and up to 1 km wide. The gold-bearing bed is 0.3-1.9 m thick. Au
grade is 0.72 to 11.82 g/m3. Gold particles differ in size and
roundness. Gold forms intergrowths with quartz, chlorite, and galena.
Gold fineness is 832-844. Adycha deposit occurs on a large spit in the
Adycha River. Deposit is about 2 km long, and the gold-bearing bed is
0.4 to 2 m thick. Au grade is 0.01 to 30 g/m3. Gold particles are
well-rounded, 2-5 mm in size; gold fineness is 740-810. Gold
distribution is irregular, radial, locally in ore pockets. Nadezhnoe
deposit is about 3 km long and occurs within a graben. The gold-bearing
bed is 0.6-3.6 m thick and occurs below 70 m of overburden. Gold grade
is 2.62-34.4 g/m3. Gold particles average 1-6 mm, and gold fineness is
640-880. Associated minerals are cassiterite, scheelite, wolframite,
magnetite, ilmenite, and arsenopyrite. Bedrock sources are Au quartz and
gold-REE veins and zones, including the Delyuvialnoe deposit. Lazo
deposit is a typical valley placer deposit, is 6 km long, and displays a
narrow radial distribution. Gold-bearing bed is 1.33 m thick and buried
0.2 to 1.3 m deep. The commercial part of the deposit is 2-6 m wide.
Gold particles are 2 to 12 mm, and gold nuggets up to 5.3 g occur.
Bedrock source is the Lazo Au quartz vein deposit.</td>
<td>Rozhkov and others, 1964; Trushkov, 1971; Yu.A. Vladimirtseva,
written commun., 1985.</td>
<td>Russia</td>
</tr>
<tr class="odd">
<td>Q</td>
<td>54</td>
<td>01</td>
<td>64 33 24N</td>
<td>64.5566666666667</td>
<td>142 49 34E</td>
<td>142.826111111111</td>
<td>Au</td>
<td></td>
<td>Verkhneamursk</td>
<td>Placer Au</td>
<td></td>
<td>Average grade of 2.6-650 g/m3 Au.</td>
<td></td>
<td>730-969</td>
<td></td>
<td><p>District consists of the Solov'ev and Urusha-Oldoi subdistricts.
The largest placer in the Urusha-Oldoi subdistrict is the Khaiktinsky
placer, and the largest placer in the Solov'ev subdistrict is the
Dzhalinda placer.</p>
<p>Dzheltulak subdistrict includes the valleys at the headwaters of the
Bolshoi Dzheltulak River and the middle part of the Tynda River that are
both western tributaries of the Gilyui River. This lode and placer
district has been known for a long time but only placers have been
mined. A major fault in the subdistrict, the Dzheltulak shear zone,
separates the Getkansky and Kurbatovsky Proterozoic plutons to the north
from the Anosov pluton in the south. Intermittant mining has occurred on
placers of the Ilichi, Baldyglia, headwaters of Bolshoi Dzheltulak, and
Burpaly Rivers; and on numerous placers of the Tynda River, tributaries
of the Burpaly River, and headwaters of the Bolshoi Dzheltulak River.
All placers are spatially associated with the Dzheltulak shear zone, a
major fault that separates the Getkansky and Kurbatovsky Proterozoic
plutons to the north from the Anosov pluton in the south. The largest
placer in the Dzheltulak subdistrict is on the Bolshoi Dzheltulak River
that is a southern tributary of the Gilyui River, and contains an
alluvial valley-type placer that was discovered in the period 1893-96.
Approximately 1.3 tonnes gold were mined by 1959. In 1954-58, the placer
reserves were recalculated based on use of a 250-liter capacity dredge
that started operating in 1980. At the beginning of dredge operations,
the placer was 22 km long, 114 m wide, and the gravel deposit 4 m thick.
Average content of native gold is 228 mg/m3, proven reserves are 2474
kg, and the fineness of gold is 887. The deposit is now 70% mined out.
The Khaiktin placer deposit occurs in the Bolshoi Oldoi River valley, a
large tributary on the north side of the Amur River. Placers in the
Khaikty River valley have been known since the early 1900's. The
Konstantinovka and Orogzhan placers were intensely mined. Based on
questionable data, over 2000 kg Au was produced from the Khaikta River
valley through 1925. The Khaiktin deposit is a valley type, is 28.8 km
long, and occurs along the flood plain of the Bolshoi Oldoi and Khaikta
Rivers. The width of the flood plain ranges from 500 to 1000 m and
alluvium thickness is less than 6.4 m. Gold-bearing sediments contain
pebbles with sand, gravel, ooze, clay, and boulders. Bedrock consists of
gneiss, granite, amphibolite, and diorite with a well-developed
weathering crust. Bedrock has a smooth upper surface, with a relief of
0.5 to 1.2 m. Gold fineness is very fine (0.25 mm) 6.47%, fine (0.25-1.0
mm)-41.6%, medium (1.0-3.0 mm)-38.81%, and large (more than 3
mm)-13.12%. Average fineness is 876. The gold-bearing bed is 0.6 to 3.6
m thick. Nuggets are not found. Thirty-four percent of the area of the
deposit has permafrost. The deposit was explored by prospect pits and
drill holes across an area of 400 x 20 m. Only a small portion (3.5%) of
the placer deposit is mined. The Dzhalinda placer deposit is the largest
in the Amur Region. Total production exceeds 120 tonnes gold. The
deposit has numerous lode sources, including the Kirovka gold-quartz
deposit associated with granodiorite intrusions and metamorphic gold
occurrences hosted in greenschist. The deposit is over 45 km long,
averages 250-300 m wide, and alluvial deposits are 5 m thick. The placer
was discovered in 1867 by N.P. Anosov, and was the first economic placer
to be mined in the Verkhnee Priamur'e. Deposit was mined by hand until
1929 (production of 39 tonnes Au). Dredges have been used since from
then through the present. Gold occurs throughout the section and maximum
grades occur near the bedrock. The fineness is high and averages 940.
Placer deposits of the Yankan River are derived from the Kirovka lode
deposits. Placer deposits have been known since 1867 and have been mined
since 1871. The placers are over 15 km long, average 350 m wide, and
have alluvium about 6 m thick. Gold fineness is 930. The Nagim placer
deposit occurs in the western part of the Solov'evsky subdistrict, and
is a very thick gold-bearing deposit (up to 50 m thick).</p></td>
<td>B.V. Pepelyaev, written commun., 1964; Trushkov, 1971; Yu.A.
Vladimirtseva, written commun. 1987; Oleinikov, 1992.</td>
<td>Russia</td>
</tr>
<tr class="even">
<td>R</td>
<td>53</td>
<td>01</td>
<td>70 20 02N</td>
<td>70.3338888888889</td>
<td>134 16 35E</td>
<td>134.276388888889</td>
<td>Au</td>
<td></td>
<td>Kular</td>
<td>Placer Au</td>
<td></td>
<td>Average grade of 0.5-26 g/m3 Au.</td>
<td></td>
<td>391-962</td>
<td></td>
<td>District contains several placer deposit types, including buried
Paleogene-Neogene placers that occur at the base of superimposed
depressions, and small late Quaternary ravine placers. District contains
about 10 known placer deposits of variable length and width.
Gold-bearing beds are covered by up to 150 m of overburden. Gold
particles are small in size (0.1-3.5 mm) and average 0.8-1 mm. Flattened
gold particles predominate. Gold-bearing gravels form elongate zones.
Valleys are up to 1,200 m wide and contain paystreaks up to 100 m wide.
Equant and elongate weathering crusts up to 30-50 m thick are
widespread. Most of the placers formed by water reworking of weathered
rock during the early Oligocene. The bedrock sources of the placer
deposits are Au quartz veins and zones, and Au-REE and Au-Hg deposits.
Major deposits are at Kara-Onkuchak and Burguat. Kara-Onkuchak placer
occurs in an ancient buried valley, consists of a gold-bearing bed up to
10-20 m thick, and is formed in an early Oligocene alluvial gravel with
quartz pebbles (50%) cemented with light-gray sandy clay. Overburden is
about 100 m thick. Average size of gold particles is 0.5-1 mm and
fineness 795-815. Burguat bench placer deposit of early Pleistocene age
occurs on an aggradation-denudation terrace that is 15-20 m above river
level. Pay gravels consist of quartz pebbles (20%) and clastic rock of
the Vekhoyan Formation. Gravels are cemented with argillaceous sand. Pay
gravels are underlain by a weathering crust in the middle section of the
river and by Miocene gravel in the lower reaches of the river. Some
gold-bearing layers occur in the thalwegs of buried ancient valleys.
Gold-bearing gravel beds range up to 10-15 m thick. Average size of gold
particles ranges from 0.88 to 1.44 mm. Gold fineness is 680-886, with
the maximum in the middle portion of the deposit.</td>
<td>Ivensen and others, 1975; Samusikov and Sergeenko, 1974; Yu.M.,
written commun., 1963; Amuzinsky and others, 1988.</td>
<td>Russia</td>
</tr>
<tr class="odd">
<td>R</td>
<td>54</td>
<td>01</td>
<td>69 41 50N</td>
<td>69.6972222222222</td>
<td>140 21 57E</td>
<td>140.365833333333</td>
<td>Sn</td>
<td></td>
<td>Polousnensky</td>
<td>Placer Sn</td>
<td></td>
<td>Grade ranges up to hundreds g/m3 cassiterite .</td>
<td></td>
<td></td>
<td></td>
<td>District contains several tens of cassiterite-bearing zones. The
Deputatskaya and Omchikandinskaya placer deposits are the most
important. Placers in this district occur near granite intrusions and
are closely related to bedrock sources. Placers occur close to bedrock.
Sn placers are mostly alluvial, and more rarely are eluvial-diluvial.
The most important Sn placers are associated with lode stockworks.
Amount of cassiterite is variable, and may be associated with wolframite
and sometimes with bismuth nuggets. Cassiterite is coarse and 40-50% is
larger than 7 mm. Boulders of cassiterite occur. Example of deposits are
at Deputatsky Creek and Omchikandya Creek. Deputatsky Creek deposit
occurs in a broad valley with multiple, well-formed terraces. Overburden
ranges from 3-4 m to 8 m thick. Distribution of cassiterite is rather
regular. Within the mineralized layer, finer-grained cassiterite occurs
in the upper portion, and coaster-grained cassiterite in the lower
parts. Bedrock source is the Polousnensky lode deposit. Omchikandya
Creek placer deposit occurs in a broad valley with multiple. well-formed
terraces. Deposit forms a continuous wide band that completely fills the
valley. The deposit is more than 3 km long and is either not overlain or
overlain only by a few meters of overburden. The pay zone is 20-30 m
thick. Minerals are cassiterite (larger than 7 mm fraction of 40-50%)
and wolframite. Cassiterite to wolframite ratio of 2:1 to 3:1. Bismuth
nuggets to 1 kg are common. Lode source is the Polyarny deposit.</td>
<td>O.G. Epov and G.S. Sonin, written commun., 1964; Trushkov, 1964,
1971.</td>
<td>Russia</td>
</tr>
<tr class="even">
<td>R</td>
<td>54</td>
<td>02</td>
<td>68 16 42N</td>
<td>68.2783333333333</td>
<td>141 38 40E</td>
<td>141.644444444444</td>
<td>Au</td>
<td></td>
<td>Khatynnak-Sala</td>
<td>Placer Au</td>
<td></td>
<td>Grade ranges up to 10-15 g/m3 Au.</td>
<td></td>
<td></td>
<td></td>
<td>District contains several gold placer deposits at several horizons.
The placers are short. Gold is fine and platy. Placer gold occurs in
gravel overlying Paleozoic limestone. One example is at Khatynnak-Sala
Creek that occurs in a broad creek valley with multiple, well-developed
alluvial terraces. The alluvial placer is 7.5 km long and about 90 m
wide. The gold-bearing placer is 0.2-1.8 m thick. Gold has also
accumulated in fissures and cavities in the Paleozoic limestone bedrock
to depth of 1 m. The placer deposit is overlain by 5 to 8 m of
overburden. Gold is fine and platy and often occurs in intergrowths with
quartz and calcite. Gold is associated with zircon, ilmenite, magnetite,
pyrite, galena, and chalcopyrite.</td>
<td>O.G. Epov and G.S. Sonin, written commun., 1964; Trushkov,
1971.</td>
<td>Russia</td>
</tr>
</tbody>
</table>