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Research paper−60−Synthesiology - English edition Vol.9 No.2 pp.60­­­–73 (Sep. 2016) as reference materials essential for the chemical analysis of geological materials around the world, such as for the development of methods of chemical analysis for geological materials, accuracy management for day-to-day analysis, and preparation of calibration curves to gauge instrumental analysis.Generally, when analyzing the chemistry of geological materials, massive samples are ground into powders by using various crushers. Because natural rocks are aggregates of various minerals, from the perspective of the representativeness of the sample, a certain amount (hundreds of grams to several kilograms) of the sample is ground and homogenized, and a portion of these powders is sampled and analyzed for chemistry. Fundamentally, geochemical reference materials are obtained by grinding source rocks into powders and then storing these powders in bottles or other containers (Fig. 1).The history of the development of geochemical reference materials began in 1949 when the U.S. Geological Survey (USGS) issued the G-1 (granite) and W-1 (diabase) reference materials. In Japan, the Geological Survey of Japan (GSJ) began developmental studies in 1964, and the first reference material, JG-1 (granodiorite), was issued in 1967. Thereafter, the responsibility was passed to the Research Institute of Geology and Geoinformation of GSJ, and about 50 types of reference materials have been prepared in the subsequent 50 years (Table 1). More than 10,000 units of these GSJ geochemical reference materials have been distributed 1 Introduction (what are geochemical reference materials?)The chemical analysis of elements, a part of the geological survey activities of the Geological Survey of Japan (GSJ), is an essential technique for examining geological characteristics and geologic history. For example, chemical analysis is essential in the utilization of mineral resources for exploration and formation analysis of ore deposits, the evaluation of their feasibility as resources, among others. As such, accurate chemical analyses are desired in the trading of actually mined ores. In addition, chemical analysis is necessary for environmental assessments, such as those considering contamination by specific elements and the ways these elements migrate. The geological materials that are the targets of a geological survey, such as rocks, ores, minerals, soils, and sediments, contain various elements in high concentration. For example, there are as many as 10 elements of relatively high contents that are referred to as major components of rock samples such as silicon, aluminum, iron, etc. These components of high concentration affect each other in chemical analysis; therefore, to chemically analyze specific elements accurately, the effects from other elements must be identified accurately. Therefore, for accurate chemical analysis, it is effective to use reference materials with similar major component contents (similar effects from high-content elements) and with the target element concentration determined. These reference materials for accurate chemical analysis of geological materials are called “geochemical reference materials,” and they are used - Reliability improvement in the analysis of geological materials-The Geological Survey of Japan has issued about 50 reference materials over the past 50 years. They have been used all over the world to improve the reliability in chemical analysis of geological materials. Geological samples of rocks, ores, minerals, soils, sediments, etc. generally contain various elements at high concentration levels. For accurate chemical analysis, it is necessary to use geochemical reference materials that contain major components at similar levels to the samples to be analyzed and predetermined concentration of target elements. In this paper, scenarios to develop geochemical reference materials for Japan and the rest of the world are described. Methods for selecting and grinding sample materials, the determination of reference values, and data sharing are also reported.Development and utilization of geochemical reference materialsKeywords : reference material, geochemistry, chemical analysis, geological materials, sample grinding [Translation from Synthesiology, Vol.9, No.2, p.60–72 (2016)]Takashi OkaiResearch Institute of Geology and Geoinformation, GSJ, AIST Tsukuba Central 7, 1-1-1 Higashi, Tsukuba 305-8567, Japan E-mail: Original manuscript received August 26, 2015, Revisions received October 6, 2015, Accepted October 16, 2015

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