1) The existence of ancient sites, sand-buried or lying on the wind-eroded ground and slept for many centuries in the Taklamakan desert was not the discovery of the modern scientific expeditions, but was noted and described by Chinese travelers and historians of early days. For instance, Hauan-Chuang, the great Buddhist pilgrim in the 7 th century, described the abandoned sites in the great sandy desert to the east of the Niya oasis along the southern route, in his famous travelling notes of “Records of the Western Countries in the time of the T'ang”. Li-Kuangyin, a historian in the Ch'ing dynasty of the 19 th century, in his “Studies of the Western Countries in the Han dynasty, with Illustrations” tried to correlate the territories of the ancient kingdoms with the oases of the present day, with a perplexing conclusion stating that the territories of Shanshan, Chiemo, Chingchueh, Yuni, Siauyan, Junglu, etc. described in the Han Annals have been abandoned to the “Gobi”. The impact to the modern scientific world, however, was made by the expeditions of European geographers, historians and archaeologists between the later part of the 19 th and the early 20 th centuries. Particularly the great successes brought by Sven Hedin of Sweden and Sir Aurel Stein of England aroused activity in other countries and expeditions were sent to Sinkiang from several countries. Among them the explorations of the Japanese party led by Count K. Otani evoked a great interest in the Japanese, although its scientific research was of a special field, i. e. the study of remains of Buddhism and Buddhist temples in the ancient period in Sinkiang. The modern scientific explorations uncovered various aspects, particularly, the historical importance of the region. The Old Silk Road was not only the routes through which currents of trade moved, the most important export from the East was the silk of the Seres, i. e. of the ancient Chinese, but the currents of cultural intercourse linking the Far East with the West and with India. As for the ruined sites, the periods of the final abandonment were established fairly accurately by the dated Chinese documents and other archaeological remains which revealed that some were abandoned between the 3 rd and the 4 th centuries, many were in the 8 th century and still others in later periods up to the 15 th century. 2) In contrast to the successful achievements in the fields of cultural history and archaeology, geography has been concerned in the many problems and riddles, especially concerning the ruined sites on the edge of the Taklamakan. What were the main causes which led to the abandonment ? Under what conditions could the ancient settlements flourish in the drift-sand desert, where no water is available today ? Why were many of the sites buried in sand or were partly sand-covered and the surrounding areas abandoned to desert ? No historical documents and archaeological remains give clues to these problems. The problems have received much attentions in many countries and many geographershave attempted to offer explanations, presenting various theories. The classical exemple was the desiccation hypothesis presented by E. Huntington of the U. S. A. in 1907, which aroused a sensational debate in various countries. He tried to explain the complicated problems simultaneously by assuming the pulse of climate, the existence of a fairly long-continuing pulse of precipitation within historical times in Inner Asia. Many geographers, however, were not in favor of his theory and some felt that he was claiming the progressive desiccation during historical times. The attention and the interest of many geographers and historians were focused on the causes of abandonment of the sites, though no definite record was preserved, and a variety of assumed causes were presented.
Geological and mineralogical characteristics of the carbonatites are summarized comparing with those of the sedimentary carbonate rocks. Then, kinds and natures of the mineral deposits genetically related with the carbonatites and alkaline complexes are described briefly based on the literatures. Emphasis was given especially on such kinds of mineral deposits as niobium, cerium, phosphorus and vermiculite deposits. Many occurrences of the mineral deposits, not only of the above-mentioned types, but also of strontium, barium, zirconium, titanium, iron, copper and molybdenum, are listed in table with literatures.
It is a common knowledge that the geography of mineral production has attracted small number of geographers comparing with other fields of economic geography. Even though there have been several articles dealing with mineral production, most of them have been concerned with either the distribution pattern of mining activities, or the commodity or commodity-in-area approach. It is, however, expected that the analysis of more dynamic characters of mineral production, which are also covered by the field of mineral economics, would bring more fundamental basis to develop this field of geography. Two factors, localized occurrence and exhaustibility, are the most important characteristics of mineral production and these must be considered as basic to the study of the geography of mineral production. In other words, the former sets the distribution pattern of mineral production, and the latter and its derivatives differentiate the pattern. The problems which stem from these two factors distinguish the mineral industries from other industrial activities. It is the purpose of the geography of mineral production to evaluate the extent and nature of the factors, to analyze the regional characteristics and to describe the areal associations brought by mining activities. In addition, some consideration should be given to the phases which the factors have brought drastic interruption in the sequent occupance of a mining region. The geographers of mineral production should pay more attention to the importance of the dynamic characters of mineral production and their associated problems and try to consider the trends of mining activities on the basis of analysis of geographical research. The rise and fall of mineral production have a close relationship with socio-economic problems of mining regions, so that the analysis of the factors appraise more fundamental understanding of the ever-increasing importance of minerals in our economy. The writer owes a debt of thanks to Dr. Shinzo Kiuchi and Dr. Osamu Nishikawa of the Department of Human Geography, University of Tokyo, for their stimulating criticisms and constructive advices. He is also deeply grateful to Dr. E. Willard Miller of the Department of Geography and Dr. John J. Schanz, Jr. of the Department of Mineral Economics for their patient guidances and kind suggestions while he was studying at the Pennsylvania State University.