SEM observation, dynamic light scattering measurement, powder X-ray diffraction measurement, and differential thermal analysis were carried out on quartz powder ground by a planetary ball mill and on fine-grained quartz that was further separated by elutriation. The results of this study showed that the crystallite size of α-quartz decreased with increasing milling time, but there was a trend of increasing the aggregate size. The amorphous phase was evaluated from the XRD baseline intensity at around 2θ=11°. The amount of amorphous phase generated by the ball milling increased in α-quartz with milling time. As a result, the areas of both endothermic and exothermic peaks corresponding to the α-β and β-α phase transitions decreased and finally disappeared completely. Even by decreasing the areas of endothermic and exothermic peaks, no obvious changes were observed in the α-β and β-α phase transition temperatures. The results of this study suggest that differential thermal analysis can be used as a useful tool to evaluate the initial process of amorphization in α-quartz.

JIS standards of X-ray fluorescence spectrometric analysis of iron ores (JIS M 8205), cements (JIS R 5204), and refractories (JIS R 2216) define the uniformity test for glass beads to validate their analytical results. Three methods were applied for the preparation of six glass beads by mixing of 0.4000 g of quartz (SiO₂, 99.8 mass%), which is the most refractory material to be fused, and 4.0000 g of Li₂B₄O₇ on chartae, oblate films and polyethylene films for 300 seconds, and finally the mixture was fused in Pt vessel. The six glass beads of quartz were prepared to satisfy their most rigid analytical tolerance value of 0.15 mass% using JIS R 2216 refractories. The tolerance values of six glass beads prepared by fusion of a mixture of quartz and Li₂B₄O₇ on chartae, oblate films, and polyethylene films for 300 sec yielded 0.35, 0.46, and 0.24 mass%, respectively, which are not completely consistent with JIS analytical values. On the polyethylene films, quartz and Li₂B₄O₇ were mixed for 120, 60, and 10 sec, and fused in Pt vessel. The results of mass% exhibit that six glass beads fused by mixing for 60 sec on polyethylene films yielded 0.13 mass%, which is satisfied with the analytical tolerance value estimated by JIS R 2216.

Information collected from geological newsmagazines in 2020 is reviewed. First topic is mineral resources such as mineral commodity summary in USA, porphyry deposits, international cooperation for critical minerals, an environmental analysis of the smelters with a use of tree rings, and mineralogy of lithium. Second topic is the pyrrhotite distribution map in USA. It is prepared for construction aggregates to prevent failing concrete. Third, the event that led to closing a geoscience departure is reviewed.

一般社団法人日本鉱物科学会2020年度第2回定例理事会議事録