Petrography and relic spinel chemistry of small ultramafic bodies disseminated in the northeastern Honshu Island, Japan are studied at Wakasennin, Yakeishidake, Motai, Kawatabi, Kinkasan, Marumori and Surikami from north to south, in comparison with the large, well studied large ultramafic bodies at Hayachine and Miyamori in the South Kitakami terrain. Ultramafic rocks from Kinkasan contain olivine, and those from Marumori and Surikami bear both olivine and orthopyroxene, but others are completely serpentinized. However, chromian spinels commonly survive in their cores. Chromian spinels from the northern areas (Wakasennin, Yakeishidake, Motai, Kinkasan) are highly chromian (Cr#0.65-0.90), implying their origin in arc-related depleted mantle. However, chromian spinels from Marumori and Surikami show relatively low Cr#(0.35-0.65), implying their origin in an arc-related, relatively fertile mantle. These Cr-rich and -poor spinels are both present in the Hayachine and Miyamori bodies. However, chromian spinels from Kawatabi show a unique, higher-Mg# trend in the Cr#-Mg# diagram, and this provides the first identification of provenance for the high Mg# detrital chromian spinels reported from the Lower Jurassic Shizugawa Group in the South Kitakami terrain. Analogous high-Mg# spinels are known from anhydrous peridotites from the Mariana forearc. Comparison with the reported spinels from the Carboniferous conglomerate of the Nedamo zone indicates that the erosion of these ultramafic bodies started as early as the Carboniferous time. The difference in spinel chemistry between the Abukuma (Surikami) and Kitakami (other bodies) terrains is not significant, indicating pervasive exposure of the Early Paleozoic Hayachine-Miyamori forearc ophiolites in the Late Paleozoic-Mesozoic forearc areas of Northeast Japan, including the Abukuma terrain.
Mineral assemblage in the deep interior of the giant planet such as Super Earth is the challenging subject for the experimental study because of the significant difference between experimentally producible pressure and real pressure at the interior of the giant planet. One of the plausible ways is an approach from the analogue material, and then titanate is expected to behave as analogue of silicate even at low pressure. Although the long-held expectation was the decomposition of ABO3-type compound into AO+BO2 assemblage at the ultrahigh pressure, present experimental work showed that 2/3AO+1/3AB3O7 assemblage is the densest and this model may be more stable at deeper interior of the giant planet. Experimental study also found Th2S3-type structure in Ti2O3 which structure corresponds to post-postperovskite phase. The dense assemblage and phases found in titanate are promising for investigating the behavior of silicate under ultrahigh pressure such as the deep interior of the giant planet, super earth.
Here I briefly review the results of crystallographic studies for high pressure phases of aluminum hydroxides, δ-AlOOH and δ-Al(OD)3 by using X-ray and neutron diffraction. The neutron diffraction study for δ-AlOOH and δ-(Al0.86Mg0.07Si0.04)OOH resolved the long-standing problem of the symmetry of this phase. The observed reflection conditions clearly show that the space group of pure δ-AlOOH is P21nm with ordered hydrogen bonds, whereas that of δ-(Al0.86Mg0.07Si0.04)OOH is Pnn2 or Pnnm with disordered hydrogen bonds. The space group of δ-Al(OD)3 was first reported as Pnam with disordered hydrogen bonds by powder X-ray diffraction, but it was subsequently revised to P212121 with ordered hydrogen bonds by the neutron diffraction study. From the viewpoint of polyhedra and hydrogen bond network, I present how their symmetry and order-disorder state of hydrogen are related to the polyhedra in their crystal structures.
New combinatorial ion implantation system was developed to improve the throughput of experimental results for materials science. A new system was constructed by the mask and the digital scanning system to control ion dose in the substrates. In this paper, the application to find the visible luminescence of the semiconducting zinc oxide film was introduced.
Mr. Shinmatsu Ichikawa was a prominent mineralogist, although he was an ordinary citizen and not in government service. He lived from the late Meiji Period to the early Showa Period. He taught in elementary school and teacher training school despite not having a regular university education. He was self-taught in mineralogy and foreign language, and became a pioneer in the field of crystal morphology. His contributions include observations of the etched surfaces of natural minerals and of artificial etched quartz crystals and quartz spheres. He observed the etch pits, etch hillocks, growth hillocks and striations on the surfaces of several minerals found in Japan, engraved their positions, shapes and distributions on metal plates, and discussed his observations. He built the Ichikawa Mineral Laboratory in his house in 1918 to store his collection of minerals, rocks and fossils (more than 7000 specimens in all). His collection includes big quartz crystals twinned after Japan law from the Otome mine, twisted quartz from the Naegi region, amethyst crystals from Mt. Ametsuka and the Yusenji mine, natural etched minerals from various parts of Japan, and many minerals from the North America. The Laboratory is a historic cultural site in his hometown. Its preservation and enlightenment activities are cooperatively carried out by the local government and a neighborhood self-governing body.