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The crystal chemistry of anorthite with low content of albite (An92.0 Ab3.4), part of a rapidly cooled anorthite megacryst occurring in 1940 ejecta from Miyake-jima volcano, Japan, has been investigated using a single-crystal X-ray diffractometer and an electron microprobe analyzer with wavelength dispersive X-ray spectroscopy (EMPA-WDS). The structure was refined in space group P1̅ and cell parameters, a=8.182(6) Å, b=12.883(4) Å, c=7.092(4) Å, α=93.19(4)°, β=115.91°(4), γ=91.18°(4). The final weighted R-factor is 3.77% for 1549 reflections. Averaged T-O distances are 1.681 Å for T1(0), 1.674 Å for T1(m), 1.677 Å for T2(0) and 1.680 Å for T2(m), indicating Al occupancies of 0.501, 0.453, 0.472, and 0.496, respectively. These results suggest that the Al/Si-distribution in the tetrahedral framework is highly disordered (QOD=0.06), which results in bisection of the c-period in Al/Si ordered anorthites (c∼14 Å). Chemical composition of the refined crystal obtained by EMPA-WDS is (Ca0.93 Na0.03 Fe0.02□0.01)(Mg0.01 Al1.94 Si2.05)O8. The extra-framework site-populations consist of the following two: (1) A(000) site occupied by Ca (86%), Na (8%), Fe2+ (4%) and □(2%), and (2) A(zi0) site by Ca (100%). The Al/Si tetrahedral framework is hence pseudo-face-centered in symmetry (C1ʩ so that both extra-framework cations and their defects appear to reduce the symmetry of the overall structure to P1ʮ Although the Al/Si disordered anorthite can be interpreted as a metastable phase, the observed chemical non-stoichiometry may stabilize such a metastable structure by introducing minor -Si4+-O-Si4+- bonds into the tetrahedral framework and anti-phase-boundary.

Zircon from granitic rocks, Japan is classified into two major types; based on the minor element content determined by electron microprobe, a heavy rare earth element (HREE)-U-Thpoor (Type I) and a HREE-U-Th-rich (Type 2). Zircons characteristically occurring in common granites of type-1 are relatively poor in HREE including Y and Sc, up to 2.72 wt% HREE2O3; up to 0.44 wt% ThO2; up to 2.10 wt% UO2, while zircons characteristically occurring in granitic pegmatites of type-2 are much richer in HREE including Y and Sc, up to 18.99 wt% HREE2O3; up to 11.09 wt% UO2; and up to 6.58 wt% ThO2 However, analyses showing a significantly high amount of REE+Y almost certainly represent altered zircon and/or accidental analysis of inclusions (Hoskin & Schaltegger 2003). Only crystal structure of zircon free of inclusions and zoning (type-2; Takenouchi granitic pegmatite) was refined to R = 4.3 % and for the first time has been confirmed that zircons of type-2 exist as a single-crystal phase in nature. .

The crystal chemistry of volcanic allanites from both the Youngest Toba Tuff (YTT), Sumatra, Indonesia and SK100 volcanic ash beds (SK100-VAB), Niigata, Japan has been examined by electron microprobe analysis (EMPA), Fourier-transform infrared spectroscopic analysis (FTIR), and single-crystal structure analysis. In the FTIR study, based on the Diamond ATR accessory, YTT and SK100- VAB allanites were observed to have different OH contents, respectively: the former has 0.64 wt% H2O (OH: 0.40 apfu.), while the latter has 1.65 wt% H2O (OH: 1.00 apfu.). The crystal structures of these two allanites have been refined to individual R indices (3.64 and 4.25) based on 1350 observed reflections (, Fo, > 4sig, ) measured using a single-crystal diffractometer with MoKα X-radiation. The OH-poor YTT allanite has a shorter b axis, a longer c axis, and larger β value than the relatively OH-rich SK100-VAB one. The bond valence sums of O4 (accepter oxygen for H atom) and O10 (donor oxygen for H atom) are 1.962 and 1.709 v.u. for YTT allanite (valence sum: 3.671 v.u.) and 1.754 and 1.271 v.u. for SK100-VAB one (valence sum: 3.025 v.u.). The difference from the ideal total bond valence value (4.00 v.u.) of O4 and O10 in YTT allanite (0.33 v.u.) is smaller than that in SK100-VAB (0.98 v.u.). These difference values are also broadly consistent with the corresponding differences in OH content between the YTT (OH: 0.40 apfu.) and SK100-VAB allanites (OH: 1.00 apfu.) determined by FTIR- ATR. Chemical analyses, FTIR-ATR and crystal structure refinement of YTT and SK100-VAB allanites yielded the following crystal chemical formula: YTT: (Ca0.83Mn2+ 0.06Fe2+ 0.11)(La0.24Ce0.32Pr0.04Nd0.11Sm0.02Th0.04Ca0.21)(Al0.73Fe3+ 0.19Ti0.08)(Al0.89Fe3+ 0.11)(Fe2+ 0.22Fe3+ 0.62Mg0.16)(SiO4)Si2O7O1.6(OH)0.4, SK100-VAB: (Ca0.81Fe2+ 0.13Mn2+ 0.06)(La0.22Ce0.34Pr0.05Nd0.13Sm0.02Th0.02Ca0.22)(Al0.76Fe3+ 0.19Ti0.05)Al1.00(Fe2+ 0.73Fe3+ 0.17Mg0.10)(Si0.96Al0.04O4)Si2O7O(OH). Therefore, it is concluded that welding of the Youngest Toba Tuff caused the following post-crystallization changes to occur in YTT allanite: oxidation of Fe2+ to Fe3+, release of H2, and the concomitant replacement of OH− by O2−. These oxidation and dehydrogenation processes advanced during the welding to thereby produce oxyallanite. Oxyallanite had been reported only in laboratory studies where it was produced by heating natural allanite. Our report on natural oxyallanite suggests that it may be present in other welded silicic volcanic rocks as well.

Idrialite from Skaggs Springs, Sonoma County, California, was studied by microbeam and bulk analyses; the former include micro X-ray diffraction (μ-XRD), electron microprobe (EMP), and micro Fourier transform infrared (μ-FTIR) spectroscopic analyses, and the latter include powder XRD analysis, thermogravimetry-differential thermal analysis (TG-DTA), and carbon isotope analysis. Careful observation under a stereo-microscope clearly disclosed that the examined sample is composed of yellow and brown parts. The yellow parts were identified as idrialite with high crystallinity, whereas the brown ones were confirmed as amorphous matter by μ-XRD. Furthermore, the μ-FTIR spectra revealed that the yellow and brown parts contain hydrophobic and hydrophilic compounds, respectively. EMP analysis showed no chemical zoning and homogeneous distribution of S-bearing molecules in the yellow parts. TG-DTA disclosed that the present idrialite of the yellow part left no residue on heating up to 740 °C; this thermal behavior is similar to that of the other natural organic matter in liquid states such as petroleum and crude oil. The carbon isotopic composition was analyzed using an elemental-analyzer isotopic-ratio mass spectrometer (EA/IRMS). The δ13C value of the idrialite is −24.429 ± 0.090‰ (vs. V-PDB), which is akin to carbon isotopic compositions of the typical higher-plant triterpenoids contained in sedimentary organic matter. Both the yellow part (idrialite) and brown part (amorphous organic matter) occur on the coexisting minerals (opalline silica, metacinnabar, and siderite); the textural relationship indicates that the organic matter precipitated after crystallization of the associated minerals. Thus, it is suggested that the organic molecules were migrated by hydrothermal fluids and then separated into hydrophobic (idrialite) and hydrophilic (amorphous organic matter) molecules during the cooling process. Following the separation, idrialite was crystallized and then the amorphous organic matter was precipitated at the final stage of the hydrothermal activity.

Euhedral dissakisites from Trimouns dolomite mine, France, is compositionally zoned. Back-scattered electron (BSE) images reveal that each of the described dissakisite crystals has three distinct compositional zones: normal zoned core (Mg-rich), oscillatory zoned middle (Ca–Al-rich) and homogeneous rim (Fe–ΣREE-rich). The latter zone with Fe2+ > Mg corresponds to allanite-(Ce). Dissakisite-(Ce) also displays pronounced zoning in Fe/Mg which may suggest that the temperature of crystallization continuously decreased from core to rim. Despite a systematic increase in Fe/Mg of the dissakisite with an allanite rim, there is no monotonic decrease in the REE zoning: the normal zoned core and homogeneous rim are rich in La, Ce and Pr, but the relatively REE-poor oscillatory zoned middle is relatively abundant in Y, Sm and Gd. Discontinuous variation in REE content of the dissakisite, with the allanite rim may indicate a localized change in either the relative concentration of various ligands or pH of the crystallizing fluid. Observations under the polarizing microscope confirm that the different zones have simultaneous extinction. These chemical and optical observations suggest that epitaxial crystallization of dissakisite, from Trimouns, passes through three formation stages. The ternary Fe2+–Mg2+–(Al + Fe)3+ diagram illustrates that in general dissakisite can be classified into two groups, (Al + Fe)3+-rich and an Mg-rich; dissakisite from Trimouns belongs to the former group. Chondrite-normalized REE patterns of dissakisites from Trimouns are similar to those of allanites formed by hydrothermal fluids. In conclusion, it is clear from the above two geochemical characteristics that dissakisites from Trimouns are of (Al + Fe)3+-type, and were derived from hydrothermal fluids.

Earth Evolution Sciences, Life and Environmental Sciences, University of Tsukuba, �-�-� Tennodai, Tsukuba ��5-8572, Japan Geological Survey of Japan, AIST, �-�-� Higashi, Tsukuba ��5-8567, Japan Chemical Analysis Division, Research Facility Center for Science and Technology, University of Tsukuba, �-�-� Tennodai, Tsukuba ��5-8572, Japan Center for Tsukuba Advanced Research Alliance, University of Tsukuba, �-�-� Tennodai, Tsukuba ��5-8572, Japan

We have investigated allanite phenocrysts and the apatite and zircon inclusions they contain from three localities: (1) SK100 ash beds, Niigata, Japan, (2) the youngest Toba Tuff (YTT), Sumatra, Indonesia, and (3) the Bishop Tuff (BST) in eastern California, to gather geochemical inferences about the magmas from which these phases crystallized using an electron microprobe. Back-scattered electron (BSE) images reveal the presence of euhedral crystals of apatite (5–30 μm) and zircon (5–20 μm) incorporated into euhedral phenocrysts of allanite. Textural evidence suggests that apatite, zircon and allanite crystallized in that order. Furthermore, the chondrite-normalized REE pattern of apatite inclusions in these allanite phenocrysts resembles that of apatite in syenites and unfractionated carbonatites. This characteristic suggests that apatite inclusions crystallized from relatively alkaline magmas rich in REE, CO32− and PO43−. Such a magmatic signature could perhaps represent that of a boundary-layer melt. In addition, the F/Cl and Mn/Fe values of the apatite inclusions imply that the relative SiO2 contents of such magmas increase in order SK100 → YTT → BST. Variations in Y and Hf contents and Zr/Hf value among the zircon inclusions also show that they crystallized from mafic (SK100), intermediate (YTT), and felsic (BST) magmas. The host rocks are similar to magnetiteseries granites from Japan, according to two characteristics of the allanite: (1) appreciable amounts of Mg (0.078–0.165 apfu ) and Ti (0.057–0.137 apfu ) and (2) chondrite-normalized REE pattern. The petrogenetic processes envisaged for crystallization of allanite phenocrysts and their apatite and zircon inclusions can explain differences in (1) the REE pattern between allanite and apatite, (2) variations in minor elements among allanite, apatite and zircon, and (3) occurrences of minerals associated with the allanite phenocrysts.

The isotopic compositions of Sr and Nd were analyzed for sixteen samples of allanite-(Ce) from Mesozoic–Cenozoic granitic rocks in Japan (11 samples of an Mn-rich type, and five samples of an Mn-poor type). The Mn-rich allanite-(Ce) crystals have an initial 87Sr/86Sr value in the range 0.70811–0.71398 and an initial 143Nd/144Nd value in the range 0.512148–0.512471, whereas for crystals of Mn-poor allanite-(Ce), the analogous intervals are 0.70499–0.70704 and 0.512547–0.512606. There is a negative correlation between 87Sr/86Sr and 143Nd/144Nd values. The trend of these isotopic data for Mn-rich and Mn-poor allanite-(Ce) is parallel to that for ilmenite- and magnetite-series granitic rocks from Japan, respectively. This parallelism suggests that the genesis of these two groups of allanite-(Ce) is related to that of ilmenite-series and magnetite-series granitic rocks. The characteristics of allanite-(Ce) can shed light on the petrogenesis of granitic rocks.

Dissakisites from Trimouns dolomite mine, France, have two kinds of single crystals: chemical-zoned and homogeneous types. Back-scattered electron microprobe (BSE) images of these dissakisites reveal both Ca–Al rich dark zones and Fe-ΣREE rich bright zones. Crystal structures of three dark and two bright zones in a chemical-zoned dissakisite and of a homogeneous zone in unzoned dissakisite were refined to individual R indices (about 3.0–5.0%) based on 1,400 observed [|F 0| > 4σF 0] reflections measured with MoKα X-radiation using the single crystal diffractometer. The differences in brightness between their BSE images arise from those in coupled substitutions of the elements occupying A2 and M3 sites. The main reason for these differences is that ten-coordinated A2 polyhedra and M3 octahedra are directly linked through their shared edge, which creates a great potential for making this coupled substitution. This zoning indicates that formation of the whole zoned crystal, where each zone could be grown steadily with its crystallographic axes mutually parallel to each other, may be identified as autoepitaxy.

Nous avons caracterise avec une microsonde electronique la composition chimique de vingt-deux echantillons d'allanite-(Ce) provenant de roches granitiques au Japon. Les images formees par les electrons retrodiffuses montrent que l'allanite-(Ce) est homogene ou zonee de facon oscillatoire, normale ou irreguliere. Treize echantillons font preuve de quantites importantes de Mn (0.14-0.59 apfu). Les cristaux riches en Mn sont plus longs (2-6 cm) que les cristaux a plus faible teneur en Mn (0.5-2 cm). Ces deux groupes d'allanite-(Ce) different considerablement dans leurs spectres de terres rares normalises par rapport a une chondrite. L'allanite-(Ce) a faible teneur en Mn est relativement enrichie en terres rares legeres (TRL), comme c'est generalement le cas dans l'allanite des roches ignee, tandis que l'allanite-(Ce) riche en Mn montre un enrichissement dans les terres rares moyennes (TRM). La relation entre les deux groupes se decrit par une substitution couplee: Mn 2+ (TRM, TR lourdes) 3+ ⇄ Ca 2+ + TRL 3+ . La presence d'allanite-(Ce) manganifere dans les granites de l'arc insulaire japonais, de meme que les indices de mineraux du groupe de l'epidote riches en Mn et en terres rares dans les gisements de manganese, semblent temoigner d'un lien avec les phenomenes de subduction. Les roches granitiques contenant l'allanite-(Ce) pauvre en Mn font partie de la serie de roches granitiques a magnetite, tandis que les roches granitiques contenant l'allanite-(Ce) riche en Mn correspondent a la serie a ilmenite, et se seraient formees de magmas enrichis en composants volatils. C'est donc dire que la teneur de l'allanite-(Ce) en M serait un indicateur de l'origine des roches granitiques.

The crystal structure of allanite from granitic pegmatite, the Daibosatsu Pass, Yamanashi, Japan, has been refined under the constraint of chemical composition determined by electron microprobe analysis of rare earth elements. Back-scattered-electron images and X-ray element maps of the allanites show that each of their crystal grains has chemically homogeneous distribution of major elements. A typical formula for the chemistry is: (Ca0.920☐0.080)Σ1.000(La0.238Ce0.443Pr0.048Nd0.100Sm0.019Th0.042Mn0.008☐0.102)Σ1.000(Al0.607Fe0.3173+Ti0.076)Σ1.000(Al1.000)(Fe0.5432+Fe0.3653+Mn0.055Mg0.037)Σ1.000(SiO4)(Si2O7)O(OH).The crystal structure of allanite, monoclinic, a 8.905 (1), b 5.7606 (5), c 10.123 (1) Å, β 114.78°(1), space group P21/m, Z = 2, has been refined to an unweighted R factor of 3.46% for 1459 observed reflections. Although the H atom position was not determined on the Difference-Fourier map, inspection of the bond valence sums demonstrates that the H atom is uniquely located at the O10 atom and involved in a hydrogen bond to O4. A systematic examination as to crystal chemistry of allanites suggests that the isolated SiO4 tetrahedron has the largest distortion of three kinds of the tetrahedron containing Si2O7 groups in the allanite structure. This observation is common to the epidote group minerals, while the larger distortion of A2 sites caused by occupancy by REE in allanites contrasts with the smaller one of A sites in other epidote group minerals. In the allanite groups the bond angles between the O10–H bond and hydrogen bond H···O4 are found to range from 170 to 180°.Compilation of the chemical compositions of the title allanite and the others from granitic rocks, Japan, which reveals Th-incorporation as the coupled substitution of 3Th4+ + ☐ (vacancy) ⇌ 4REE3+, provides an explanation for the observation that higher Th concentrations characterize allanites from the island arcs. The ternary Al2O3-Fe2O3-ΣREE diagram illustrates that allanites are grouped, according to their origins, into three classes suggestive of tectonic backgrounds for the crystallization localities; (1) intracontinental, (2) island arc and (3) continental margin.

Chemical evolution of ferrocolumbites from the Ishikawa-yama granitic pegmatites, Fukushima, Japan, has been revealed by electron microprobe analysis. The compositions of ferrocolumbites are different among sample locations, which are within about 1 km distant from each other. Three discernible trends in compositional variations in ferrocolumbites have been observed: (1) a homogeneous crystal trend, with low Ta/(Ta + Nb); (2) a trend with oscillatory zoning related to Ta and Nb; (3) a trend with patchy zoning related to Fe and Mn. Oscillatory zoning of ferrocolumbite is intimately related to crystal growth in magmatic process. Ferrocolumbite with patchy zoning shows parallel extinction and doesn’t appear to have the complementary distribution of octahedral cations due to some coupled substitutions on the plots of partition coefficient (each zone/the assumed average) against ionic radius. These facts and the curved boundaries of patchy zoning suggest that patchy zoning of ferrocolumbite has been produced by topotaxy in the open system.

Valid identification of microinclusions, which is essential to understanding the genesis of minerals, can require more than traditional petrology that is focused on their chemical compositions. By combining determination of chemical composition with X-ray characteristic imagery of atoms, electron microprobe analysis of individual microinclusions provides a means by which to identify their chemical structures or mineral species. Here we apply this technique to identification of microinclusions and show the results obtained substantiate the origins of colors for sunstones: A transparent red-color of the Oregon sunstone is due to the distribution of mixtures of both native coppers and cuprites in oval-shaped thin films, while the transparent-green type is due to the distribution of their similar mixtures in short microcolumns.

The solubility and behavior of lead in feldspar are elucidated by EPMA and X-ray photoelectron spectroscopy (XPS; also known as ESCA) analyses for green orthoclase (amazonite) from Broken Hill, New South Wales, Australia. The role in the crystal structure establishes Pb cation as PbAl2Si2O8 endmember for the orthoclase solid solution, and the maximum quantity of PbAl2Si2O8 is 3.8 mol% in the green orthoclase. The lead cations, except the one existing in the orthoclase lattice, namely structurally bound Pb, occur in the green orthoclase by the following two ways; 1) as galena inclusions, and 2) as unidentified Pb-bearing micro-inclusions. The chemical shift for Pb atom in the green orthoclase was investigated by XPS, and compared with those in a Pb-metal, Pb-oxides, and a galena. Differences in the binding energy between Pb in the green orthoclase and other Pb-substances show distinctly that most of the Pb is not present as impurities like micro-minerals, but as structural components in green orthoclase. Crystal chemical consideration of Pb affords us infallible discrimination of solubility of PbAl2Si2O8 endmember rather than PbAlSi3O8. The existence of PbAl2Si2O8 as the main endmember in green orthoclase exhibits the charge-coupled substitution in the extra framework and the tetrahedral site; K++Si4+ ↔ Pb2++Al3+. Inhomogeneous distribution of Pb cation within the single crystal shows that the condition of Pb cation in green orthoclase structure is unstable.

Thallium leucite, TlAlSi2O6, has been synthesized at 450°C for 7 days, under ambient conditions, by the transformation of dehydrated analcime NaAlSi2O6 in the presence of excess TlCl. This substitution of Tl for Na leads to confirmation of a thallium-leucite pseudomorph after analcime. Their optical properties, X-ray powder diffraction patterns, electron microprobe analysis, infrared spectra, and X-ray photoelectron spectroscopy have characterized the synthetic Tl-leucites. The IR spectra show that the mid-IR modes T-O stretching and T-O-T bending vibrations for TlAlSi2O6 are more resemblant of those for analcime than for leucite, KAlSi2O6. This resemblance implies that Tl cation enters the W-site rather than the S-site in the analcime structure: Na (S) + H2O (W) ⇋ □ + K (leucite) ⇋ □ + Tl (Tl- leucite), where □ represents an S-site vacancy. The mechanism of this substitution is supported by the crystal chemical constraints: inasmuch as the S-site is smaller than the W-site, Tl+ cations being larger than Na+ plainly prefer the latter site to the former. One inference from the binding energy for Tl+ by XPS is that Tl+ occupies the extra-framework site in synthetic leucite pseudomorph, rather than the smaller tetrahedral site. The difference in Al/Si disordering between analcime and leucite and the nonstoichiometry due to the solid solution of the □Si3O6 component into the leucite structure may provide a fundamental insight into understanding why TlAlSi2O6 deviates from the trend defined by K-, Rb- and CsAlSi2O6 leucite series on the a-c parameter diagram, inasmuch as these three cations in the leucite structure occupy the W-sites. Finally, synthesis of TlAlSi2O6 leucite has an implication for the existence of other polymorphs due to different degrees of Al/Si disordering, except for high- and low-temperature leucites already known: natural leucites crystallized directly through igneous processes are different from those formed by substitution of K for Na in analcimes.

Thallium leucite, TlAlSi2O6, has been synthesized at 450°C for 7 days, under ambient conditions, by the transformation of dehydrated analcime NaAlSi2O6 in the presence of excess TlCl. This substitution of Tl for Na leads to confirmation of a thallium-leucite pseudomorph after analcime. Their optical properties, X-ray powder diffraction patterns, electron microprobe analysis, infrared spectra, and X-ray photoelectron spectroscopy have characterized the synthetic Tl-leucites. The IR spectra show that the mid-IR modes T-O stretching and T-O-T bending vibrations for TlAlSi2O6 are more resemblant of those for analcime than for leucite, KAlSi2O6. This resemblance implies that Tl cation enters the W-site rather than the S-site in the analcime structure: Na (S) + H2O (W) ⇋ □ + K (leucite) ⇋ □ + Tl (Tl- leucite), where □ represents an S-site vacancy. The mechanism of this substitution is supported by the crystal chemical constraints: inasmuch as the S-site is smaller than the W-site, Tl+ cations being larger than Na+ plainly prefer the latter site to the former. One inference from the binding energy for Tl+ by XPS is that Tl+ occupies the extra-framework site in synthetic leucite pseudomorph, rather than the smaller tetrahedral site. The difference in Al/Si disordering between analcime and leucite and the nonstoichiometry due to the solid solution of the □Si3O6 component into the leucite structure may provide a fundamental insight into understanding why TlAlSi2O6 deviates from the trend defined by K-, Rb- and CsAlSi2O6 leucite series on the a-c parameter diagram, inasmuch as these three cations in the leucite structure occupy the W-sites. Finally, synthesis of TlAlSi2O6 leucite has an implication for the existence of other polymorphs due to different degrees of Al/Si disordering, except for high- and low-temperature leucites already known: natural leucites crystallized directly through igneous processes are different from those formed by substitution of K for Na in analcimes.

Anorthite megacrysts are common in basalts from the Japanese Island Arc, and signally rare in other global fields. These anorthites are 1 to 3 cm in size and often contain several corroded Mg-olivine inclusions. The megacrysts generally range from An94Ab4Ot2 to An89Ab6Ot5 (Ot: other minor end-members, including CaFeSi3O8, CaMgSi3O8, AlAl3SiO8, □Si4O8) and show no chemical zoning. They often show parting. Redclouded megacrysts contain microcrystals of native copper with a distribution reminiscent of the shape of a planetary nebula. Hydrocarbons are also present, both in the anorthite megacrysts and in the olivines included within them. Implications of lateral variations in the Fe/Mg ratio of the included olivines, in Sr-content and in Sr-isotope ratio of the anorthite megacrysts with respect to the Japanese island arc, relate to mixing of crustal components and subducted slab-sediments into the basaltic magmas.

This paper reviews on crystal chemistry of plagioclases and geochemical roles of their megacrysts including native coppers and hydrocarbons, discussed in two parts.Part I. Structural classification of feldspar compositions can be allocated into four types; feldspar, paracelsian, hexacelsian and hollandite structures. Though the phase relation between the first and the second types has been open to question, recent probing of their isotropic temperature factors and bond-valence theory to the M-sites intensifies that feldspars are in the wide stability field from low to high temperatures under low pressures, and that high pressure and low pressure are the preference field for paracelsians. Though very common in north-east part of Japanese island and Izu-Bonin arcs, anorthite megacrysts have never been found in other districts in Japan and have been rare in world-wide occurrences. Native coppers, verified by chemical shift method of EPMA and X-ray microdiffraction, are found to be included by anorthite megacrysts from Japanese island arc and by labradorite ones from the continental margin of North America. These anorthites in the basaltic lavas are of approximately 1 to 3 cm size and often contain several corroded Mg-olivines scattering as single crytals less than a few mm long. The plagioclase megacrysts show no chemical zoning, but the anorthites with the Al/Si ordered state have partings developed in places whereas the labradorites are of the AUSi disordered structure indicative of high temperature type. Each role in their plagioclase structure establishes Mg, Fe, Al and Si cations as a few minor endmembers of CaFeSi3O8, CaMgSi3O8, AlAl3SiO8 and_??_Si4O8 for the solid solutions. Furthermore micro-inclusions of native zinc, copper and brass scattering in the red-clouded anorthite megacryst frozen by the supercooling environment could have an implication for a precusor to Kuroko deposits. Review (1) discusses both structural tolerance of plagioclases and their megacrysts including native coppers.

The microstructure and the M, temperature were systematically investigated for three types of Ti-Ni-Nb shape memory alloys, Ti 50-x / 2 Ni 50-x / 2 Nb x , Ti 50 Ni 50-x Nb x and Ti 50-x Ni 50 Nb x covering a wide composition range, by utilizing optical microscopy, SEM, EPMA, X-ray diffraction and DSC. Consequently, the following results were obtained. Addition of Nb promotes phase separation

Trace level determination of nickel in silicate rock samples has been achieved using secondary ion mass spectrometry (SIMS) with kinetic energy filtering. Standard rock references, issued by the Geological Survey of Japan, were fused into glass and used as standards for the SIMS analysis. Due to interferences from the glass matrix, the secondary ion of mass 60 was only useful for Ni, although the secondary ion was interfered mainly by CaO+. The contributions of these molecular ions were deconvolved by a least squares regression. Good linear correlation between results after the deconvolution and the Ni concentration in the glass standards was obtained. The uncertainties of the SIMS analysis depend strongly on the degree of contribution of CaO+ molecular ion. Such a method of SIMS analysis is especially useful to study the detailed behavior of Ni on a micro-scale in Ca-poor materials.

An analytical method using an electron probe microanalyser (EPMA) has been developed to enable rapid determination of trace Zn contents in mafic silicates. Total matrix correction factors of atomic number, absorption and fluorescence ( ZAF correction factors) for Zn are constant and virtually independent of solid-solution composition and mineralogy. Zn analysis confirmed by inductively coupled plasma-optical emission spectrometry (ICP-OES) reveals that this EPMA method is capable of analyzing Zn within only 30 s at a detection limit of 50 ppm. Preliminary studies of Zn abundance indicate that: (1) clinopyroxenes in skarn deposits tend to vary their Zn contents in accordance with the metal type, 500 ppm for the W type; (2) Zn contents of granitic biotites in the Ishikawa area, northeastern Japan, increase from 290 to 610 ppm with the advance of crystallization; and (3) Zn contents of chlorite in weathered granitic rocks are almost equivalent to those of its primary biotite. Therefore, this rapid EPMA method may have considerable potential for the use of trace Zn as a metallogenetic indicator and as a marker for crystallization or alteration processes.

The oxidation of Feto Fe, the release of H2, and the concomitant replacement of OH by O would produce an oxy-equivalent of allanite (CaREEAl2FeSi3O11O(OH)) (Dollase 1973). The reaction Fe + OH↔Fe+ O+ 1/2H2 is formally equivalent to the oxy-reaction observed in other hydrous Fe -bearing silicate minerals, such as mica and amphiboles (e.g., Hogg & Meads 1975; Ferrow 1987). However, occurrence of oxyallanite (CaREEAl2FeSi3O11O(O)) in natural environment has never been reported. The purpose of the preset study is to discuss occurrence of natural oxyallanite. Chemical compositions and crystal structures of the allanites from two rhyolitic rocks--(1) Youngest welded tuff from Toba (YTT), Sumatra, Indonesia and (2) volcanic ash from SK100 (SK100-VAB), Niigata, Japan--were determined by electron microprobe analysis and single crystal diffractometer, respectively. Despite the close similarity, in chemical composition, between YTT allalnites and SK100 ones, their unit-cell parameters are distinct from each other. The former have shorter b axis and longer c axis and larger β value in comparison with cell parameters of the latter. FT-IR analysis shows that YTT allanites have both the smaller OH-absorption band area and the shift of its bands to higher wavenumbers as compared to SK100 ones. Welding of the ash flow tuff including the allanites preformed in Youngest Toba welded tuff would cause them to undergo oxidations, dehydration and replacement. The sequential reaction would result in producing the present YTT allanite, namely oxyallanite. Although oxyallanite was only obtained by heating the natural allanite (e.g., Armbruster et al. 2006), this study first reports that oxyallanite may commonly occur in welded rocks at high temperatures.

Nine Yamato-74 chondritic meteorites have been classified based on a simplified version of the Van Schmus-Wood classification. The result is as follows : Yamato-74348 is H4 chondrite, Yamato-74349 and -74379 are H4-5 chondrite, and Yamato-74244,-74250,-74265,-74306,-74319 and -74382 are H5 chondrite.

Quantitative micro-analysis of silicate glasses has been developed using secondary ion mass spectrometry (SIMS). The standard rock references, issued by the Geological Survey of Japan (GSJ), were fused into glass beads and used as standards for SIMS analysis. Thirty eight elements at major, minor and trace concentration levels, were analyzed simultaneously on the standard glasses using an energy-filtering technique. In the concentration range of the glass standards, linear relationships were established for the following elements: Li, Be, B, Na, Mg, Al, P, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Cu, Rb, Sr, Y, Zr, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Hf. The typical accuracy of the analyses are within 10% of recommended values of GSJ standards for the elements over 1 ppm.

Na/Al convergence has been observed in groundmass of chondrules and matrix from seven Yamato-74 (H, L, 4-5) chondrites. On the other hand, Na/Al dispersion has prevailed in groundmass of chondrules and matrix from Yamato-74191 (L3) chondrite. The results suggest that : (1) Primordial liquid droplets as precursors of the chondrules might be derived from a rapidly cooling solar nebula by fractional condensation. (2) The hot liquid droplets thus formed might be cooled instantaneously by radiation loss in the cooling nebula. (3) The chondrules as quenched products might be subjected to mutual collision during accumulation in the cold nebula. (4) Planetesimals accumulated by the chondrules might be transferred from the place of birth to an unknown hot region in the proto solar nebula.

Internal chemical inhomogeneity in a single euhedral olivine from the Murchison C2 chondrite has been visualized by a two dimensional element concentration map technique, as applications of automated electron probe microanalyzer. The olivine crystal has a double layered structure which consists of rather homogeneous inner region (from 0 to 200μm in dia., Fa27) and outer region with a zonal structure (from 200 to 300μm in dia., Fa27∼Fa33). Al, Cr-rich, Fe, Mg silicate inclusions exist in the outer region of the olivine. These features might have been established in a cooling solar nebula, reflecting the presence of two different environmental conditions during crystal growth of the single olivine.