4.2.1.1 Reserves and Resources

China's magnesite is rich in resources and excellent in quality. It is one of the dominant minerals in China. As for magnesite, China occupies an important position in the world. By the end of 1996, the total number of explored magnesite occurrences throughtout the country are 27 with a retained reserves of magnesite up to 3,001 million tons, of which reserves of A+B+C grades are 1,312 million tons, accounting for 43.72% of the total. The retained reserves of magnesite increased by more than two times in 1996 over the 1960 (Table 4.2.1).

Table 4.2.1 Statistics of increase of magnesite retained reserves in China (ore:¡Á106t)

China has a large potential in magnesite resources.It is expected that there are 8,000 million tons of magnesite reources retained.

According to Mineral Commodity Summaries,1996, published by the USA Bureau of Mines the total magnesite reserves in the world are 2,500 million tons, reserves bases 3,400 million tons, and resources are about 12,000 million tons. Except for China, which occupies the first place as for magnesite reserves, the other countries with abundant magnesite resources are Russia (reserve bases 730 million tons, reserves 650 million tons), Korea (reserve bases 750 million tons, reserves 450 million tons), Turkey (reserve bases 160 million tons, reserves 65 million tons).

4.2.1.2 Characteristics

Magnesite reserves in China are distributed in 9 provinces and regions: Hebei, Liao-ning, Anhui, Shandong, Sichuan, Tibet, Gansu, Qinghai, Xinjiang, of which Liaoning has the largest reserves, accounting for 85.62% of the total national reserves, the Shandong is the next, accounting for 9.54% of the total. The other provinces or regions which have comparably large reserves are Tibet, Xinjiang and Gansu (Fig. 4.2.1, Table 4.2.2).

From the tectonic point of view, it can be seen that the national magnesite reserves are mainly distributed in five, tectonic units of first category. They are; Sino-Korea quasi-platform (accounting for 95.52% of explored reserves), Yangtzi quasi-platform (accounting for 0.32% of explored reserves), Qilian fold system series (accounting for 0.94% of explored reserves), Gangdisi-nianqingtanggula fold system series (accounting for 1.95% of explored reserves), Tianshan fold system series (accounting for 1.08% of explored reserves). The extra-thick magnesian carbonate rock formation in Sino-Korea quasi-platform is the major potential magnesite ore district of our country.

The stratigraphic times, in which the stratum controlled crystalline magnesite mineral in China occurred, are very many, the main ones of them are the Archean, proterozoic, Devonian and Triassic Periods, of which the Proterozoic Era is the most important period for magnesite occurrences, its reserves account for 95.34% of the nation's total ones.

The stratum-controlled magnesite deposits and ore layers in different periods are mainly occurred on the medium and overlying stratum levels of every stratigraphic unit. For instance, marble group of Mingcunbu of Fengzhishan Cluster in the Archean Era (Shandong), Hongheniu on the upper part of Zhanhuang Cluster in the Archean Era (Hebei), Dezhiqiao Group on the upper part of Liaohe Cluster in the proterozoic Era (Liaoning),Yemashan Group in the Proterozoic Era (Gansu), Dengying Group in the Upper Series of Sinian System (Sichuan), Sharming Group on the upper part of Middle series, Devonian System (Xinjiang), Bulilali Group in the Upper series of Triassic System (Tibet).

Table 4.2.2 The main magnesite deposits in China

¢ÙThe scale of deposits is in accordance with  The Dividing Standard of Scales of Deposits issued by National Mineral Reserves Commission in 1987: Large reserves are more than 50 mil.t; medium-sized reserves in between 10~50 mil.t; small reserves less than 10 mil.t.

Several obvious characteristics of magnesite in China are as follows:

1) Reserves are highly concentrated and most of them are large and medium-sized deposits. As above-mentioned that magnesite reserves in China are concentrated in Liaoning and Shandong two provinces, the total reserves of them account for 95.16% of national total. Among 27 magnesite occurrences in China, there are 11 large-sized ones (reserves are more than 50 million tons), their retained reserves account for 95.11% of the national total. There are 5 medium-sized ones (reserves 10~50 million tons) with retained reserves of them accounting for 4.05% of the national total. These large, medium-sized occurrences have generally better mining condition and are suitable to open-pit mining, mechanized operation and large-scale management.

2) Excellent ore quality makes it highly competent in the international market. Of magnesite reserves, first and second grade ores with MgO more than 43% account for 53% of the total. Of them, magnesite reserves of first grade (including super grade products) are 1,170 million tons, accounting for 37.58% of the total retained reserves, those of second grade are 480 million tons and account for 15.42% of the total retained reserves. Due to good quality and low price, it is exported annually in large quantities, and occupied an important position in international market.

3) The carbonate rock type deposits are in the majority. Of 27 national magnesite deposits, 21 belong to stratum-controlled magnestie deposits in the magnesian carbonate stratum. This type of deposits features large scale and excellent quality of ores, and possesses great industrial value, their retained reserves are 2,988 million tons and account for 95.99% of the total. 2 magnesite deposits belong to pyrometasomatic type and weathering eluviation type in the ultra basic rocks. Their retained reserves are 1 million tons, accounting for 0.03% of the total reserves. There is 1 deposit of hydromagnesite of lake series type in quaternary period with retained reserves of 99 million tons, accounting for 3.18% of the total reserves of the country. Additionally, there are 3 magnestie deposits associated with iron and talc deposits, having retained reserves of 25 million tons, accounting for 0.8% of the total reserves of the country.

4) Exploration level is high, so is the development level. Of 27 magnesite deposits in China, 12 deposits are explored and their retained reserves are 2,607 million tons, accounting for 86.8% of the total retained reserves, 10 magnestie deposits have detailedly investigated, and their retained reserves are 213 million tons and account for 7.1% of the national total retained reserves. 5 deposits are only in the reconnaissance stage, and their retained reserves are 18 million tons, accounting for 0.6% of the total retained reserves of the country. Of 27 magnesite deposits, 18 deposits have been already developed with reserves of 2528 million tons, accounting for 84.2% of the total country's retained reserves.