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日本科学技术厅资源调查委员会本着促进尖端科学技术进一步开发的目的,对世界主要稀有金属资源进行了调查,并于1986年4月提出了《主要稀有元素资源的有效利用报告》。该报告对稀有元素的划分原则是:在地壳中元素的存在度低于0.1％(1000ppm)以下者为稀有元素,大于此限者为非稀有元素。在地壳上的90种元素(海洋地壳除外)中有79种为稀有元素。
In order to promote the further development of cutting-edge science and technology, the Commission of Resources Survey of Japan Science and Technology Agency conducted a survey on the world’s major rare metals resources and submitted a “Report on Effective Utilization of Major Rare-Element Resources” in April 1986. According to the report, the principles for the division of rare elements are: rare earth elements below 1% (1000 ppm) in the earth’s crust, and non-rare earth elements beyond this limit. Of the 90 elements on the earth’s crust (except the marine crust), 79 are rare.