Tin is one of the earliest metals, discovered and utilized by mankind. Our ancestry was able to use tin, copper and lead to produce bronze utensils as early as in the Shang Dynasty. Because of its softness, ductility, chemical stability, corrosion resistance, fusibility and  small friction coefficient, and the nontoxic property of its salts, tin and its alloys have a wide application in modern national defense, modern industry, most advanced science and technology and human livelihood.   

China is abundant in tin resources, has been a major country-tin producer for a long time, occupying a leading position in the world both in reserves and production.

3.13.1 Resources

3.13.1.1 Reserves and Resources   

By the end of 1997, the tin accumulative explored reserves had reached 5.7109 million tons, with retained reserves totaling up to 3.9073 million tons, of which the reserves of A+B+C categories amounted to 1.9721 million tons, making up 50% of the total retained reserves. From 1955 to 1996 the tin retained reserves increased nearly four times over 40 years (Table 3.13.1)

Table 3.13.1 Retained tin reserves in China(¡Á106t)

According to the data of USGS and Mining USBM the world's tin reserves and reserve base are seven million tons and ten million tons respectively. Besides China among countries with richer tin reserves there are: Brazil (with reserves amounting to 1.2 million tons and a reserve basereaching 2.5 million tons); Malaysia (1.2 million tons and 1.2 million tons); Thailand (0.94 million tons and 0.94 million tons); Indonesia (0.75 million tons and 0.82 million tons). Additionally Zaire, Bolivia, Russia, Australia and others also possess a certain reserve tonnage. China ranks first in the world in terms of reserves; based on a  comparison of the reserves of A+B+C categories in China with the reserve bases of these countries China stands second only after Brazil.

3.13.1.2 Characteristics

Tin resources of China are distributed over 15 provinces and autonomous regions, among which Yunnan possesses 1.28 million tons of retained reserves, accounting for 31.4% of China's total; Guangxi--1.3404 million tons, making up 32.9% of the total; Guangdong--408,200 tons, representing 10.0% of the total; Hunan--362,500 tons, constituting 8.9% of the total: Inner Mongolia--328,700 tons, accounting for 8.1% of the total; Jiangxi--260,400 tons, making up 6.4% of the country's total. The retained reserves of above-mentioned six provinces (or regions) constitute 97.7% of China's total.    

The distribution of China's major tin deposits and the present state of their development and utilization are shown and listed in Fig. 3.13.1 and Table 3.13.2 respectively.

China's tin deposits are mostly of large and medium sizes, with the Gejiu deposit of Yunnan and Dachang deposit of Guangxi representing the most famous, and world-class super-large polymetallic-tin deposit areas.

The Gejiu deposit is located within the area of Gejiu city (Yunnan province), 2140 km2 in area, with tin taken as the dominant metal, and copper, tungsten, bismuth, lead, silver and other polymetals accompanied. A North-south-trending fracture divides the deposit area into two parts: eastern and western. The former one has five large tin fields, i.e. Malage, Songshujiao, Gaosong, Laochang and Kafang, while the latter possesses the Niushipo large placer tin deposit, and the Douyan, Zhuqingpo and tens of medium-small sized tin and lead deposits (occurrences). The Gejiu area has a long tin mining history. According to the historical records it produced tin as early as in the Han Dynasty. Both domestic and foreign geologists had carried out a great deal of geological investigations before New China was founded. Since the founding of the People's Republic of China a systematic geologic exploration has been conducted over Songshujiao, Laochang, and Kafang tin fields, resulting in identifying substantial explored metal reserves:1.82 million tons of tin, 1.52 million tons of copper, 3.08 million tons of lead, 0.53 million tons of zinc, 0.14 million tons of tungsten and 2,400 tons of silver. Gejiu has become a tin capital in the real sense of the term.

The Dachang tin field strides over two counties of Guangxi: Nandan and Hechi, being an old tin field with a long mining history. According to the historic records, mining began as early as in the Song Dynasty. The earliest geological survey can be traced back to the investigation made by Mr Le Sen Xun from the Geological Survey of Guangdong and Guangxi in 1928, then followed by a series of geological investigations. Since the founding of New China a great deal of geological survey, prospecting and exploration, have been carried out in this area. A Summary Report of Tin Placers Reserves of Dachang Tin Mining Area was presented in 1958, with 94,001 tons of tin, 162,666 tons of lead, 89,856 tons of zinc, 97,830 tons of antimony, and 500 tons of indium metal reserves proved. A Summary Report of Reserves of Primary Ore Deposits of the Dachang Tin Field, Nandan, Guangxi, was presented in November, 1958, with 141,900 tons of tin, 514,569 tons of zinc, 216,555 tons of lead, 109,729 tons of antimony and 20,975 tons of copper metal reserves proved.

Another character istic feature of China's tin resources is that primary tin ores are dominant, making up 80% of the country's total reserves, and placer tin is subordinate in importance, accounting for only 16% of the total.   

Only 12% of China's tin resources occur as unitary tin ores, 66% of country's total tin resources occur as the major mineral in ore deposits, and 22% of the total occur as associated and accompanying components. Associated and accompanying minerals are copper, lead, zinc, tungsten, antimony, molybdenum, bismuth, silver, niobium, tantalum, berylium, indium, gallium, germanium, cadmium, as well as iron, sulphur, arsenic, fluorite and others.   

China's tin deposits are controlled by geotectonics very distinctly and  they usually occur along specific tectonic positions in zonal distribution. These tectonic positions are:the late Palaeozoic Tianshan-Da Hinggan Ling fold belt  between Tarim-Sino-Korean block and Siberia plate;the Palaeozoic South-China fold system on the south-eastern side of Yangtze block;the marginal Pacific fold system, formed with subduction of Meso-Cen-Ozoic West Pacific plate beneath Asia Continent£» and the Tethys Himalayan fold zone formed due to convergence

Table 3.13.2 List of China's tin deposits

¢Ù unit kg/m3.

and collision between the Indian plate and Palaeo-Asian plate. Eight tin metallogenic belts were formed under the control of these tectonic zones: ¢Ù Kang-Dian geoaxis tin metallogenic belt; ¢Ú Jiangnan anteklise tin metallogenic belt; ¢Û Youjiang tin metallogenic belt; ¢Ü Nanling tin and tungsten metallogenic belt; ¢Ý Dengke-Yidun tin and polymetal metallogenic belt; ¢Þ Western Yunnan-Middle Tibet tin metallogenic belt; ¢ß Huanggang-Ganzhuermiao (Da Hing an Ling) tin and polymetal metallogenic belt; ¢à Xiao Hing an Ling-Zhangguangcai Ling tin (tungsten) and polymetal metallogenic belt.   

Magmatic activity is another important factor controlling the distribution of China's tin deposits. All the major tin deposits within various tin metallogenic belts are located in the reworked granite zones, a lot of large and medium-sized tin deposits mostly occurs along internal and external contact zones of small stocks and apophyses (swarms), resulting from remelting and palingenetic magmatism during late Yanshanian stage. For example, all the two biggest tin deposits of  China--the Gejiu deposit of Yunnan and Dachang tin deposit of Guangxi in the Youjiang tin metallogenic belt, occur along the contact of the fully differentiated, late Yanshanian biotite granite and in the host structures of the country rocks. The mineralization of the Nanling tin and tungsten metallogenic belt (involving many tin deposits and tungsten, copper, lead-zinc, tungsten-molybdenum-bismuth, niobium-tantalum, or rare earths deposits, with tin associated) had undergone primary enrichment since the Caledonian cycle,and then it was intensified gradually through various cycles until the Yanshanian cycle, when tin and tungsten mineralization came to its climax. As concerns China's another important western Guizhou-middle Tibet tin metallogenic belt, the granites related to tin deposits within its eastern sub-belt mostly belong to the Indosinian cycle; the granites, related to tin deposits within its western sub-belt, mainly represent late Cretaceous to Eocene ones, with orebodies occurring mostly in corona of rock body outshoot or in host structures of the external contact. The granites related to ore formation within the Huanggang-Ganzhuermiao (Da Hinggan Ling) tin and polymetal metallogenic belt represent moyites of the Yanshanian stage, with ore deposits located near the granite contact. The granites related to tin and polymetal ore formation within the Xiao Hinggan Ling-Zhangguangcai Ling tin (tungsten) and polymetal metallogenic belt are intrusives of various stages of the Hercynian-Yanshanian cycle, mainly including grano-diorites and cataclastic granites, usually suggestive of medium to small-sized batholiths and stocks, with tin-tungsten-molybdenum-bismuth deposits located mainly in internal zones of contact skarns, with iron-copper, iron-zinc or copper-zinc deposits occurring in external zones of skarns, and with lead-zinc deposits further outward.