The crystal structure of (Na_.45Ca_.55) (Cr_.45Mg_.55) Si₂O₆ pyroxene synthesized at 1200°C and 2.2GPa has been refined by the least squares method using 751 reflections measured with an automatic single crystal diffractometer. The weighted R factor is 0.030 for 642 observed reflections. The cell dimensions are: a=9.645Å, b=8.821Å, c=5.254Å, β=106.47°, and V=428.67ų; space group C₂/c.
Comparison of a new crystal structure refinement for the (Na_.45Ca_.55) (Cr_.45Mg_.55)Si₂O₆ pyroxene with the published refinements for five clinopyroxenes in the system NaCrSi₂O₆-CaMgSi₂O₆ indicates that the O1A1-M1-O1B2 angles correlate with the M1-O1A1 distance as two different trends reflecting the repulsion effect between the O1 oxygens and the non-bonding 3d electrons of the Cr³⁺ ion. The repulsion effect exists in the NaCrSi₂O₆ side of the miscibility gap in the system NaCrSi₂O₆-CaMgSi₂O₆, in which the Cr³⁺ ion occupies a smaller octahedral site. On the other hand, the repulsion effect does not exist in the CaMgSi₂O₆ side, in which the Cr³⁺ ion occupies a larger octahedral site.

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Distributions, paragenesis and fluid inclusions of hydrothermal minerals in the Kakkonda geothermal field, Northeastern Japan, were studied by means of the X-ray diffractometry and the microthermometry.
Many veinlets are found in Tertiary sedimentary rocks and welded tuff of the Pliocene-Pleistocene. The mineralization can be divided into three paragenetic stages: Stage IA, Kfeldspar+quartz+pyrite; Stage IB, quartz+calcite+laumontite+yugawaralite+stilbite+mordenite+pyrite; and Stage II, calcite+kaolinite+quartz+pyrite. Minerals in Stage II were formed from recent geothermal fluids.
Fluid inclusions in quartz and calcite are generally several microns in size and are liquid inclusions. Homogenization temperatures of fluid inclusions in quartz and calcite range 87-296°C and 83-217°C, respectively.
Judging from the distribution of the maximum homogenization temperatures obtained for the samples from geothermal wells (Muramatsu, 1984) and the surface, it is inferred that at least 900 meters of overburden were eroded after the mineralization.
Temperature distribution pattern around the Kakkonda geothermal field suggests that high temperature fluids ascended mainly from the deeper zone of the western area, and that some meteoric water descended from the central area at Stage I and Stage II (present day). The data on the modes of occurrence, and the distribution pattern and fluid inclusion data of quartz and calcite, indicate that most of quartz were deposited from ascending fluids in the convective geothermal system, and that calcite precipitation resulted partly from the boiling of ascending hydrothermal fluids in the vicinity of the surface.

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Daifukuji Temple rock-cliff Budda sculpture which is located halfway up on the hill near the coast of Tateyama, Chiba Prefecture was carved in 8th century on the Neogene andesitic tuff and tuff breccia alternated bed. It is sheltered by a beautiful wooden construction.
The Neogene andesitic tuff and tuff breccia are composed chiefly of augite, hypersthene, hornblende, plagioclase, and volcanic glass with subordinate amounts of fine-grained magnetite, pyrite (probably biogenic), hematite and limonite.
The surface of Budda sculpture is covered by a thick, up to several mm, crust or scab composed chiefly of minerals such as gypsum, thenardite, epsomite, mirabilite with minor amounts of halite, sylvite, aragonite and copiapite.
Rain water penetrates into the rock of the hill where sculpture is located and the water easily comes out after interaction with rocks and evaporates from the surface of rock-cliff. The water coming out from rock mass has high contents of Ca, Na, Cl, HCO₃ and SO₄ with subordinate amounts of K and Mg.
Gypsum-rich scab or crust was formed by the evaporation of such type of groundwater on the rock-mass surface. The growth of thus formed scabs or crusts and their falling off must be major reasons why the sculpture has been decayed so badly as shown by Fig 4.
Modes of occurrence of gypsum-rich scabs and indoor experiments using bore-hole cores taken from the Neogene volcanogenic sediments mass on which the sculpture was carved indicate that the increase in the thickness of the gypsum-rich scabs is unbelievably fast, probably more than 0.15mm/year.
The repeated cycle of the growth of gypsum-rich scab or crust on the surface of Neogene volcanic sedimentary rock mass and their falling off should be stopped to prevent the forth decay of this Budda sculpture. The best ways to solve this problem are considered to be (1) to minimize the down permeation of groundwater from the top surface through interstitial void and joint of Neogene volcanogenic formation by making open drainage space at the above and/or back side of the rock-cliff sculpture or by covering the top surface of the hill by unpermeable facing and (2) to keep the humidity of the room of rock-cilff sculpture as high as possible to minimize the evaporation of water extracted from the surface of the sculpture.

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A simple statistical procedure is proposed for testing the validity of fission track counts obtained by the grain-by-grain dating method. This is based on the principle that the standard deviation of grain ages for a set of counting data should be 1 after they are standardized. Accordingly, the F value (actual variance/expected variance) will be close to 1, when the dating experiment is carried out precisely and no detrital grains of older ages are included. This test, therefore, makes it possible not only to evaluate the precision of dating experiments but also to eliminate the data pertaining to detrital grains contained in volcanoclastic rocks.

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