THE CHANGMA DIAMOND DISTRICT, MENGYIN, SHANDONG PROVINCE, CHINA ------By Peter C
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THE CHANGMA DIAMOND DISTRICT, MENGYIN, SHANDONG PROVINCE, CHINA - -- -- -- By Peter C. Keller and Wan Guo-dong Since the early 196Os, Chinese geologists n recent years, the People's Republic of China has taken have conducted extensive exploration for Ia keen interest in identifying and developing its gem- diamonds. One of their most important stone resources. The most notable of these resources is discoveries to date is the Chnnglna kim- their potentially important diamond deposits. Since the berlite district in Shandong Province, Chinese initiated a concerted diamond-exploration pro- which encompasses twopipes and eight gram in the early 1960s, at least six diamond-bearing dis- dikes. The most active mine currently, the tricts have been brought into production. Four of these- Victory No. I, produces approximately 6,000 ct of diamonds annually, 20% of the Yuan River, Changde County, in Hunan Province; which are gem quality. The ore is processed Yingcheng in Hubei Province; and Linshu and Tancheng locnlly and the rough stones ore given a counties in Shandong Province-are secondary or alluvial. preliminary sort before they are sent to In the remaining two districts, diamonds are currently special factories for cutting. Large, good- mined from kimberlites: the Binhai mine near Fuxian in quality stones have been recovered at Fu County, Liaoning Province, and the Changma kimber- Changma; the largest to date weighs more lite district in Mengyin County, Shandong Province (see than 119 ct. the map in figure 1, Keller and Wang, 1986).The purpose of this article is to describe the little-known Changma kim- berlite district, one of the most important in China, and specifically the mining and processing observed at Changma by the authors in September 1985. ABOUT THE AUTHORS Generally speaking, Shandong Province, in eastern Dr. Keller, a geologisl and gemologist, is associate direclor Lhe Los Angeles County Museum of Nalu- China, exhibits extraordinary potential as a diamond pro- ral History, Los Anqeles. California; Mrs. Wan is a ducer. Including Changma, a total of 10 diamondiferous geologisi in the shindong Bureau of Geology and kimberlite pipes and dozens of diamondiferous kimberlite Mineral Resources, Jinan, Shandong Province, China, and a member of the leam that originally dikes have been identified in this mineral-rich province. discovered the Changma kimberlite district. These kimberlites are concentrated in three districts: Acknowledgments: The authors thank Dr. Chen Xiyu, Poli, and Changma. While kimberlite bodies in all Daxiao, of the Shandong Bureau of Geology and three have been shown to contain diamonds, only a few of Mineral Resources, and Mr. Li Yang, manager of them are believed to contain sufficient quantities to be the Changma mine, for arranging the visit to the mine; and their colleagues for helpful discussions. considered economical by today's standards. The authors also thank Dr. Huang Zhengzhi, of the The most important of the three kimberlite districts in Geological Museum of Beijing, for his help in ar- Shandong Province, and perhaps in all of China, is the ranging Dr. Keller's trip to China; and geologist Dr. Wang Fuquan and interpreter Mrs. Lu Dao-Ying for Changma, located near the town of Mengyin in Mengyin their invaluable services. County. The Changma kimberlite district is about 14 km All of the photos taken at the mine and treatment long and 2 km wide, and consists of two kimberlite pipes plant are by Dr. Keller. and a series of eight subparallel dikes which generally 01986 Gemological Institute of America strike to the north-northwest. The two pipes are situated 14 Changma Diamond District GEMS & GEMOLOGY Spring 1986 Figure 1. The largest diamond re- covered to date from the Victory No. 1 pipes is this spectacular 119.01 -ct yellowish octahedron in kimberlite which is ltnown as the Mengshan No. 1. The crystal, discovered in 1983, measured over 4 cm in diameter. lJhotocourtesy of the Shandong Bn- reau of Geology and Mineral Re- - sources, linan. in the center of the series of dikes and have been LOCATION AND ACCESS given the collective designation of "Victory No. The Victory No. 1 open-pit mine and its associated 1." The large open-pit mine that has resulted from treatment plant (figure 2) are located approxi- the mining of the pipes is also called Victory No. 1, mately 14 km south of the town of Mengyin, in while the most important of the eight dikes have south-central Shandong Province. Mengyin is ap- been designated Victory or Red Flag. The Victory proximately 500 km southeast of Beijing (Peking). No. 1 pipes and the Victory No. 2 and Red Flag No. Access is by train or airplane from Beijing to 1 dikes have been the most significant producers to the Shandong Province capital of Jinan. The ap- date. proximately 170-km journey from Jinan to While the quantity of gem-quality stones pro- Mengyin requires about four hours of travel by duced thus far has not been economically signifi- automobile over a well-maintained paved road cant on a world scale, fine stones as large as 119.01 through beautiful agricultural areas with exten- ct have been recovered (figure 1). Several rough sive terracing. At Mengyin, the authors first diamonds recovered from Victory No. 1 and Vic- stopped at a state-owned hotel where the papers tory No. 2 were examined at the mine office and authorizing the visit to the mine were cleared with are also described here. local authorities. From Mengyin, the Victory No. 1 Changma Diamond District GEMS & GEMOLOGY Spring 1986 15 mine is an additional 30-minute drive over paved an impressive 20,000 ct of diamonds. The dike is road. It is important to note that the Mengyin area now overgrown by peanut fields, and the treat- is generally not open to foreigners and special gov- ment plant is in ruins. ernment permission is required to visit the dia- Following the discovery of Red Flag No. 1, mond deposit. exploration continued in the area, and in Decem- ber 1968 the Victory No. 1 pipe was located. How- HISTORY AND PRODUCTION ever, mining of the pipe did not begin until Octo- Alluvial diamonds have been found at the ber 1975, when a large treatment plant was Chengjiafu mine, Tancheng County, in Shandong constructed nearby. Today, diamond production Province since the late 1940s. According to Green appears to be limited to the now relatively large (1985))the Chengjiafu mine has produced stones as Victory No. 1 open-pit mine (figure 3).The nearby large as 96.04, 124.27, and 158.79 ct. (The largest treatment plant processes about 120 tons of ore, stone is known as the Changlin diamond, which- yielding 100-150 ct of diamonds, each day. Of contrary to Green's information-the authors these diamonds, an estimated 20% are considered were told came from neighboring Linshu County.) gem quality. After the diamonds go through a The discovery of the Changma kimberlites was the rough sort at the treatment plant, they are sent to result of an intensive diamond exploration pro- Shanghai for detailed examination and cutting. gram that initially concentrated on sampling the Most of the gem diamonds are faceted at the region's river gravels. In August of 1965, after more state-owned Shanghai Diamond Factory which, than five years of work, a team of eight geologists according to Green (1985))employs about 200 cut- from the Shandong Bureau of Geology and Mineral ters. Unconfirmed reports state that diamond cut- Resources discovered their first kimberlite in the ting also takes place in the Shandong Province form of a dike (Red Flag No. 1).The dike lay dor- coastal city of Yantai (Shor, 1985) and at the col- mant until August of 1970, when mining was ini- lectively owned Beijing Diamond Factory, which tiated and a small treatment plant erected. Red employs approximately 100 workers (Green, 1985). Flag No. 1 produced diamonds until it was shut The primary organization within China for down in 1981. During its 11 years of operation, the marketing and distributing diamonds is the Na- approximately 10,000 tons of ore processed yielded tional Arts and Crafts Import-Export Corporation Changma Diamond District GEMS & GEMOLOGY Spring 1986 (Art China]. According to Green (1985), domestic from the Victory No. 1 mine were not available. gem diamonds meet only 10% of the overall pro- However, a conservative estimate supports an duction capability of China's cutting and polishing average production of 600 ct of diamonds each facilities; the remaining 90% (150,000-200,000 ct week, or over 31,000 ct a year. About 6,200 ct of rough per year) are purchased in Antwerp. As would be of gem quality. According to Green recently as 1983, the Chinese were using all of the (1985), China's total annual diamond production industrial diamonds they produced and were, in was estimated by the China Nonmetallic Minerals fact, forced to import significant amounts of Industry Corporation at between 300,000 and diamond-358,123 ct in that year alone (Green, 500,000 ct, of which about 15%-or 45,000 to 1985)-to meet their growing industrial needs. In- 75,000 ct-are gem quality. Given the importance dustry sources report that this situation has that the Chinese place on the Victory No. 1 mine, changed in the last three years: With the increased either production estimates for the mine are vastly mining of diamonds and the capability of produc- underestimated, or the figures supplied by Green ing synthetic industrial diamonds, the Chinese are (1985)are exaggerated. In view of the fact that the better able to meet their own industrial needs and Soviet Union produced an estimated 12,000,000 ct are even offering synthetic industrial material for of diamonds in 1977, the Chinese production is, by export (Bruce Komarow, Erwin Komarow, Inc., any standard, in its infancy.