3.15.1.1 Reserves and Resources

China is rich in mercury resources. the ore districts with an explored reserve now number 103, which are distributed in 13 provinces, municipalities or autonomous regions. In 1995, the cumulative explored mercury reserve (metal, the same below) stood at 143,800 tons, of which category A+B+C was 21,000 tons. As of the end of 1997, the retained reserve was 81,200 tons, of which category A+B+C was 20,200 tons. If China's category A+B+C is comparable with the world's reserve base, then the country ranks third in the world in mercury reserve, next only to Spain (90,000 tons of reserve base) and Italy (69,000 tons of reserve base), but its reserve is higher than Kirghizstan (13,000 tons of reserve base).

3.15.1.2 Characteristics    

As for the distribution of mercury reserves in China, Guizhou Province has the most abundant reserve, occupying 38.3% of the country's total. Next come Shaanxi (making up 19.8% of the total), Sichuan (15.9%), Guangdong (6%), Hunan (5.8%), Qinghai(4.4%), Gansu (3.7%) and Yunnan (2.7%). The mercury reserves of the above 8 provinces or autonomous regions combined account for 96.6% of the country's total, and those of the first 3 provinces (Guizhou, Shaanxi and Sichuan), 74%. Table 3.15.1 shows the sizes and state of development and utilization of the country's major mercury deposits and Fig. 3.15.1 exhibits their distribution.    

China's mercury resources mainly have the following characteristics:    

Firstly, the mercury localities and reserves are highly concentrated. The country's 103 ore districts with an explored reserve are predominantly centered in Guizhou, Shaanxi and Sichuan. These three provinces combined possess 55 such ore districts (accounting for 53.4% of the total number of the country's mercury districts), and have at present 60,200 tons of retained mercury reserve (making up 74% of the country's total). Less important are Guangdong, Hunan and Qinghai, of which the ore districts with an explored reserve constitute 21.4% of the country's total number of ore districts and the combined reserve, 16.3% of the country's total.

Secondly, China's mercury reserves are derived chiefly from single-mercury ore deposits, with a certain proportion from coexisting or associated ores of other deposits. Statistics show that the coexisting and associated mercury ore reserves have occupied about 20% of the country's total retained mercury ore reserve. They occur primarily in Pb-Zn and Sb-Hg deposits. In some of these deposits, the coexisting or associated mercury ore reserve is as large

Table 3.15.1 Major mercury localities in China

Notes:  In the Chinese edition of this book, there are altogether 31 mercury localities. 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. 3.15.1.

¢Ù According to the Standards for Size Classification of Mineral Deposits promulgated in 1987 by the National Committee of Mineral Resources of China, a large mercury deposit contains a reserve of over 2,000 tons, a medium-sized one a reserve of 500~2,000 tons, and a small one a reserve of less than 500 tons.


as the reserve size of a large deposit. For instance, there are 3,000 tons of associated mercury ore in the Fankou Pb-Zn deposit in Guangdong; 1,069 tons of associated mercury ore in the Qiandongshan Pb-Zn deposit in Fengxian County, Shaanxi; 7,257 tons of coexisting mercury ore in the Qingtonggou Hg-Sb deposit in Xunyang County, Shaanxi; and 5,895 tons of coexisting mercury ore in the Gongguan Hg-Sb deposit (south segment) in Xunyang County, Shaanxi. Although the associated and coexisting mercury ore reserves are considerably large, some of them are not fully used or comprehensively recovered because the technical problems of ore dressing, smelting and separation have not been solved.

Thirdly, low-grade ore is more and high-grade ore is less. China's large and medium-sized mercury deposits mostly grade 0.1%~0.3% Hg, and partly 0.3%~0.5% Hg. Deposits grading higher than 0.5% but lower than 1% are few, and only one or two deposits have a grade higher than 1%. Therefore, in light of China's industrial criteria for mercury deposits, the minimum industrial grade for the ore is set at 0.08%~0.1%. For some of its major mercury mines, the mining grades are generally 0.15%, and only 0.5%~1% at the maximum, markedly lower than those of foreign mercury deposits. In foreign countries, what is being mined is usually high-grade deposits. Examples are the following world-famous superlarge mercury deposits: the Almadon deposit in Spain (of which the Hg grade ranges from 0.6%~20% and averages 3% with the rich ore being 8£¥~10% Hg); the Ideria deposit in Slovenia (of which the lean ore grades 0.2£¥~2% Hg and the rich ore, 6£¥~7%).

Fourthly, although there are many types of mercury ore the single-mercury ore is the dominant industrial type in the country. Its industrial types of mercury ore include: single-mercury, Hg-Sb, Hg-Au, Hg-Se, Hg-U, and Hg-polymetallic. Among these, the single-mercury type of ore is not only predominant, but easily mined and smelted (requiring only a simple flowsheet). Thus it is the major target of mining and, at the pithead of the mine, the construction of an ore mining-dressing or mining-dressing-smelting complex is suitable.Metallogenic characteristics of China's mercury deposits are as follows:

1) The deposits are relatively concentrated in time and space. Most of the known mercury deposits (or occurrences) in China belong to late Mesozoic time. Of the mercury deposits listed in the Notes to the Metallogenic Map of Endogenetic Metallic Deposits in China (1987), 91% are metallogenically of Yanshanian age; and mercury mineralization of Himalayan age can also be found in western Yunnan, Tibet and Taiwan. In spatial distribution, there can be distinguished four major metallogenic regions or belts: the upper Yangtze, the Kunlun-Qinling, the Sanjiang and the South China. The upper Yangtze is the most important mercury metallogenic region in the country, of which the known mercury deposits are distributed mainly in the west-central part of the Yangtze paraplatform, i.e. in southeastern Sichuan, western Hunan, and central, northeastern and southwestern Guizhou. It is the metallogenic region with most abundant explored mercury reserve (accounting for over 75% of the country's total).

2) The mercury metallogeny occurs mainly in platform region. China's mercury deposits are located at the favorable junction between two global mercury metallogenic belts (circum-Pacific and Mediterranean). They can be found both in platform and geosyncline regions, but occurring mainly in platform region. The country's known superlarge and many large mercury deposits are primarily distributed in the Yangtze paraplatform and concentrated in the border area of Guizhou, Hunan and Sichuan. Stratigraphically, the deposits, except one or two, occur in the Middle and Lower Cambrian and have a regional stratabound characteristic. They are large in size, mostly zonal or layered in shape, and contain the aggregate explored reserve accounting for over 80% of the country's total. In addition, they are densely distributed and occur in swarms or clusters.

3) Host rocks of China's mercury deposits are chiefly sedimentary, and very few are magmatic and metamorphic. According to He Lixian et al. (1989), the mercury deposits (occurrences) in sedimentary rocks make up 97% of the country's total, and 91% of their explored reserves occur in carbonate rocks. Only 3% of the country's mercury deposits are in various types of magmatic and metamorphic rocks. Most of the deposits (occurrences) of China are distant from magmatic rocks and exhibit no metallogenic relationship with magmatism.

4) On the basis of their ore-bearing sequences (formations), China's mercury deposits can be divided into three types: carbonate, clastic and magmatic (He Lixian et al., 1989). An ore-bearing sequence is a reliable geological body with clear indicators. It not only reflects the geological background, metallogenic setting and ore-forming mode, but also facilitates the search for mercury deposits. Basic characteristics of the three types of mercury deposit are described below:

The carbonate type is most important in China. The aggregate explored mercury reserve of deposits of this type occupies more than 90% of the total of deposits of all the types. All of the superlarge mercury deposits in the country, such as the Wanshan ore field and the Shuiyinchang deposit in Guizhou, the Yangshikeng deposit in Sichuan and the Gongguan deposit in Shaanxi, belong to this type. Deposits of this type, located predominantly on the Yangtze platform, are markedly stratabound and controlled chiefly by anticline. Most of their orebodies (ore-bearing bodies) occur in layers along the beds, with some being vein-like or in other shapes.

Deposits of the clastic type are distributed mainly in the middle segment of the Kunlun-Qinling geosynclinal fold belt and the southern segment of the Yunnan-Tibet geosynclinal fold belt. Their basic characteristics are as follows: The mercury deposits (or occurrences) are all of a certain polymetallic metallogenic region (or belt) and commonly associated with other metals, forming Hg-dominant Hg-W deposits (e.g. the Muhei Hg deposit in Qinghai) and Hg-Cu deposits (e.g. the Wenshuihe Hg deposit in Yunnan); near them there are intense magmatic activities and usually small intrusions of various kinds; the ore-bearing sequence is often intercalated with volcanic sediment, has a high content of Hg, and thus is most probably the direct source of the mineralizing material.

Deposits of the magmatic type are very few in number and small in size. Some mercury deposits (occurrences) occur in granitoids and are distributed mainly in the northeast of the country (e.g. the Yingfenggou mercury deposit in Dunhua, Jilin Province), while others occur in basic intrusive dikes and their adjacent country rocks (e.g. a deposit in the Baoshan-Shidian mercury belt in western Yunnan).