3.12.1.1 Reserves and Resources

Tungsten is a preponderant mineral resource of China. Now there have been discovered 252 tungsten districts that have a total cumulative reserve (WO3, the same below) of 6.375 million tons, of which category A+B+C amounts to 2.32 million tons (36.4% of the total). As of the end of 1997, the country's total retained tungsten reserve had stood at 5.2742 million tons, of which category A+B+C had been 2.2633 million tons (43% of the total).

China is famous in the world for its rich tungsten resources. If category A+B+C reserve is equivalent to the "reserve base" of the world, the country would rank first in the world in terms of tungsten reserve. Canada (with the reserve base of 493,000 tons) occupies second place and Russia (with the reserve base of 355,000 tons) comes third. China ranks first in the world not only in tungsten reserve but also in tungsten production and export, and therefore is reputed as the country with "three firsts".

3.12.1.2 Characteristics

Tungsten reserves have been found in 21 provinces, autonomous regions or municipalities of the country, of which 8 contain a retained reserve of over 200,000 tons. They are, in decreasing order of reserve size, as follows: Hunan, Jiangxi, Henan, Guangxi, Fujian, Guangdong, Gansu and Yunnan, which aggregate more than 90% of the country's total retained reserves.

The distribution of percentages of tungsten reserves in three major economic regions of the country is: 17.1% in the coastal region of eastern China, 75.1% in central China and 7.8% in western China. The distribution, sizes, and state of development and utilization of large, medium-sized and superlarge tungsten deposits of the country are shown in Fig. 3.12.1 and Table 3.12.1 (the numbers of the tungsten localities in the Figure is consistent with those in the Table).

Table 3.12.1 Major tungsten localities in China

Notes: In the Chinese edition of this book, there are altogether 80 tungsten localities in the Table. Here only larger localities are listed, but the numbers of the localities (deposits) shown here are conformed with those in that Chinese edition so as to make them identical to the corresponding numbers in Fig. 3.12.1.

¢Ù According to the Standards for Size Classification of Mineral Deposits promulgated in 1987 by the National Mineral Reserves Commissio of China, a large tungsten deposit contains a reserve of over 50,000 tons of WO3, a medium-sized tungsten deposit a reserve of 10,000~50,000 tons of WO3, and a small deposit a reserve of less than 10,000 tons.

Characteristics of China's tungsten resources are described below:

1) Rich reserves and highly concentrated distribution.China has obtained a cumulative explored tungsten reserve of over 6.00 million tons, and still possesses a high potential and good prospects in the search for more tungsten ores and resources. In the recent 20 years, large or superlarge deposits have continuously been discovered in the tungsten or W-polymetallic mineralization-concentrated areas of the Nanling, East Qinling and West Qinling-Qilian metallogenic belts. In particular, some large or superlarge deposits, or ore segments and orebodies have been found at the depth or periphery of the mines under operation in southern Hunan, southern Jiangxi, northern Guangdong and other parts of the Nanling metallogenic belt.

Highly concentrated distribution of reserves and ore districts is a major characteristic of China's tungsten resources. Its tungsten reserves are amassed mainly in 6 provinces or autonomous regions: Hunan, Jiangxi, Henan, Fujian, Guangxi and Guangdong, which own 83.4% of the country's total tungsten reserve (the first three provinces make up 66.7% of the total), and its large and superlarge deposits mostly occur in the first three provinces.

2) A complete set of deposit types and a large variety of metallogenic processes.     Up to now, almost all known genetic types of tungsten deposits in the world, except the modern hot-spring sedimentary and W-bearing brine-evaporite deposits, have been discovered in China. The diversification and common alternation of metallogenic processes of the country's tungsten deposits have resulted not only in the formation of complex and varied deposit types but also in the common coexistence of multiple types of deposits (or orebodies) in any single ore field (or deposit). Besides, there are also modern supergene tungsten deposits of oxidation-leaching type and alluvial-placer type (see Table 3.12.2).

Table 3.12.2 Genetic types of tungsten deposits in China (Kang Yongfu et al., 1994)

3) Multiple associated components and high multipurpose utilization rate.A lot of tungsten deposits in China are associated with useful components that number as many as more than 30. They include primarily Sn, Mo, Bi, Cu, Pb, Zn, Au and Ag, and subordinately S, Be, Li, Nb, Ta, rare earths, Cd, In, Ga, Sc, Le, As, fluorite, etc. Comprehensively recovering these components in the process of ore mining, dressing and smelting is important not only for rationally developing and utilizing the mineral resources but for improving the economic efficiency of the ore mining.

4) Less rich ore, more lean ore, and low ore grade.Of China's retained ore reserve, only 20% (mainly quartz vein-type wolframite ore) grades over 0.5% (WO3); of the country's industrial reserve of scheelite ores, only about 2% has a grade higher than 0.5%. Compared with tungsten ores in foreign countries, China's scheelite ore is inferior in quality, but its wolframite ore is superior (higher in grade, larger in deposit size, and easier for mining and dressing).

5) The ores developed and utilized are commonly of wolframite and less commonly of scheelite.Wolframite has long been the target of mining in China, but of its tungsten reserve, scheelite ore is more and wolframite ore is less. Statistics indicate that, of the country's total retained tungsten ore reserve (5.2742 million tons) obtained as of the end of 1997, 71.2% is scheelite ore, 26.3% is wolframite ore, and 2.5% mixed ore. Although the scheelite ore reserve is much, the rich ore of scheelite is little, the grade is low, and the refractory ore is abundant. Furthermore, the production of scheelite ore occupies only about 10% of the total tungsten output of the country. The ore reserve of wolframite, though less than that of scheelite, includes more high-grade ore and can be easily mined and dressed. In addition, the production of wolframite ore makes up over 90% of the country's total tungsten output.

China's tungsten deposits mainly have the following metallogenic characteristics and regularities:

1) Spatiotemporally these deposits are distributed both extensively and relatively concentratedly:    In time, they are mainly of the Yanshanian metallogenic epoch (83% of the deposits belong to this epoch). In space, these deposits, especially the large and superlarge ones, are mostly concentrated in the Nanling metallogenic region (the tungsten reserves of the deposits there make up over 70% of the country's total). In addition, the deposits in southern Jiangxi, southern Hunan and northern Guangdong are even more concentrated in distribution and usually occur in swarms or clusters. An understanding of such a regularity of distribution (in swarms or zones) is of great significance to the search for, prospecting and development of tungsten deposits.

2) Horizontal zonation of deposits:    The endogenetic tungsten deposits in the Nanling region exhibit a distinctly zonal distribution. Such a zonation is manifested in varying degrees in some metallogenic belts, ore fields, or even ore deposits. An example is the southern Jiangxi tungsten metallogenic belt of the Nanling region. Wang Chengfa (1984) considered that the vein-like tungsten deposits in southern Jiangxi are characterized by a regional horizontal zoning (which is semicircular in shape and centers about the Dayuling Mountain), and can be geochemically divided into three zones: the W-Sn zone (I), the W zone (II ) and the W-polymetallic zone (III).

3) Verical zonation of deposits:    The shapes of orebodies of the quartz-vein tungsten deposits show a "5-storey" pattern of vertical variation. The conception of this vertical variation pattern was derived from the study and prospecting of the Meiziwo vein tungsten deposit in northern Guangdong by No. 932 Brigade of the Guangdong Bureau of Metallurgy and Geology. The so-called "5-storey" pattern embraces: ¢Ù a quartz-mica line (also called "the linear vein zone"); ¢Ú a sparse veinlet zone; ¢Û a dense veinlet zone; ¢Ü a parallel thin vein cluster; and ¢Ý a large independent vein. It is, in other words, a basic zone-cluster-vein model. The veins of the tungsten deposits in southern Jiangxi and southern Hunan also exhibit a similar vertical zoning. This "5-storey" model is significant for guiding the exploration, prospecting and mining of ore deposits. It should be pointed out that due to the influence of denudation and other geological factors on ore veins, not all the vein tungsten deposits can show the "5-storey" vertical variation, that means, some may only have a 3- or 4-storey pattern.