Minerals are the source of rare earth elements (REE), and knowledge of the amount of REE in different minerals is necessary for a mineralogist. We propose steady-state luminescence measurement as a quick and non-destructive method for detecting several lanthanide ions present together in the same sample. By using excitation and emission spectra of each 4f ion, rare earth ions could be easily identified. The most intense emission lines in the UV-VIS range are 336 nm for Ce3+, 420 nm for Eu2+, 596-649 nm for Pr3+ and Sm3+, 614-617 nm for Eu3+, at 478 and 573-579 nm for Dy3+, and 520-550 nm for Er3+ and Ho3+ ions. We have verified that the best excitation wavelength for each ion as follows: for Ce3+ and Eu2+, 295 nm and 336 nm; for Pr3+, 442 nm; for Sm3+, 399-408 nm; for Eu3+, 393-395 nm; for Dy3+, 348 nm; for Er3+, 377 nm; and for Ho3+, 415 nm.
The Trans Vietnam Orogenic Belt (TVOB) of Southeast Asia is thought to have formed by a continent-continent collision between the South China and Indochina cratons in Permian-Triassic times. Here we focus on the nature and origin of metamorphosed mafic rocks that are widely distributed throughout the TVOB, including rocks from the Cangshan Mountains (northern TVOB), the Red River Shear Zone and Song Ma Suture Zone (central TVOB), and the Kontum Massif (southern TVOB). Amphibolite facies metamorphosed mafic rocks are widely distributed throughout all of these areas, while granulite facies and eclogite facies metamorphosed mafic rocks occur only in the Kontum Massif and Song Ma Suture Zone, respectively. Major and trace element compositions of these TVOB metamorphosed mafic rocks indicate an overall tholeiitic affinity, but suggest a wide array of tectonic settings for the precursor mafic magmas, including volcanic-arc basalt (VAB), mid-ocean ridge basalt (MORB), and within-plate basalt (WPB). In addition, Fe-rich gabbro-derived mafic metamorphic rocks occur in the southern part of the TVOB (in the Kontum Massif). On the basis of the distributions of each type of mafic metamorphic rocks and their metamorphic grades, there were arc and oceanic crust between the South China Craton and the Indochina Craton.
Lutecite is an aggregate of microcrystalline silica; its variety with a hexagon form is known as hexalite. Textures of lutecite and hexalite from the Arz-Bord Range, in northwestern Gobi, Mongolia, and from Banyan-obo, China, were observed by optical microscopy, synchrotron X-ray diffraction, and transmission electron microscopy (TEM). Cross sections of lutecite and hexalite observed through optical microscopy show fibrous textures. TEM observations revealed that the quartz crystals constituting each fiber exhibit irregular shapes elongated parallel to , which is nearly perpendicular to (101); a width of 0.5 μm; and length of a few micrometers. The results of selected area electron diffraction analyses show that the fiber bundles have V-shaped cross textures, and the crystals are twinned according to the Reichenstein-Grieserntal law. X-ray diffraction analysis indicates a total moganite content of approximately 10 wt% in this lutecite aggregate, and moganite appears as irregular-shaped domains within quartz under high-resolution TEM.
Makovickyite [(Ag,Cu)1.5Bi5.5S9], and cupromakovickyite (Cu8Ag2Pb4Bi18S36), members of the pavonite group, have been found from the Obari mine, Yamagata Prefecture, Japan. Both minerals are the first occurrence in Japan. Makovickyite occurs as irregular particles of 30-200 μm in the chalcopyrite-rich ore, and is intergrown with the exsolution lamellae of cupromakovickyite. Both minerals are associated with bismuthinite derivatives (bismuthinite, krupkaite, aikinite), possibly cuprobismutite homologous minerals, emplectite, tetradymite and chalcopyrite. The empirical formula of makovickyite is Ag1.27Cu2.60Pb0.28Bi10.23S18 (based on ΣS = S + Te + Se = 18), which is classified as iCu-bearing makovickyite. The unit-cell parameters from the X-ray single crystal of the mineral are a = 13.2524(5), b = 4.0523(2), c = 14.6775(6) Å, β = 99.487(3)°, V = 777.44(6) Å3. The empirical formula of cupromakovickyite is Cu8.66Ag2.43Pb2.32Bi18.07S36 (based on ΣS = S + Te + Se = 36). It is inferred that these minerals have been formed by high temperature (more than 300 °C) hydrothermal solutions in which Bi activity is relatively higher than Cu.
The crystal structure of osumilite is characterized by channel-like cavities that are composed of double six-membered rings along the c-axis, which is similar to the channels of beryl and cordierite. Beryl and cordierite generally include water molecules in the channel, and these have been extensively investigated using mainly infrared (IR) spectroscopy. Two major types of water molecules have been determined, however, the water molecules in the channel-like cavities of osumilite have not been reported. Polarized IR absorption spectra of water molecules in osumilite are presented here. The polarized IR absorption spectra of oriented osumilite that was hydrothermally treated at 600 °C and under 100 MPa for 72 h revealed three pairs of split peaks with equivalent intensity. They can be assigned to ν3-I and ν1-I (3651 cm-1 and 3554 cm-1), ν3-IIa and ν1-IIa (3635 cm-1 and 3601 cm-1), and ν3-IIb and ν1-IIb (3603 cm-1 and 3551 cm-1) as well as water molecules in the channels of cordierite and beryl.
Namibite [Cu(BiO)2VO4(OH)] and hechtsbergite [Bi2O(VO4)(OH)] were found with clinobisvanite, waylandite, eulytite, beyerite and bismutite at the Nagatare mine, Fukuoka Prefecture, Japan. This assemblage occurs as secondary minerals and forms crusts and euhedral crystals associated with lepidolite, quartz, albite and cookeite. Namibite forms a dark green powder with pearly luster. Hechtsbergite is yellow, and is found as fine isolated crystals or aggregates. The compositions of namibite and hechtsbergite, determined by electron microprobe, are Cu0.98Bi1.92Al0.04O2 (V0.96Si0.07P0.02)O4 (OH) and Bi1.94Al0.01O(V1.00Si0.04)O4 (OH), respectively. The unit-cell parameters are a = 6.216(4), b = 7.384(6), c = 7.467(6) Å, α = 90.19(8), β = 108.65(7), γ = 107.36(8)°, V = 308.1(3) Å3 for namibite, and a = 6.954(5), b = 7.539(8), c = 10.870(9) Å, β = 106.87(5)°, V = 545.4(6) Å3 for hechtsbergite.
Copper silicate hydrates have been prepared by sol-gel method using stock solutions with different Cu/Si molar ratios. The synthetic gels were characterized by means of ICP-AES, TG-DTA, XRD, and EXAFS. Copper silicate hydrate gel having the chrysocolla-like structure was successfully formed in the gel samples prepared from every solution with different Cu/Si molar ratios. The local structure of chrysocolla is readily realized in the copper silicate gels regardless of the Cu/Si mol ratio involved.
Talmessite was found in veinlets (approximately 1 mm wide) cutting into massive limonite in the oxidized zone of the Uriya deposit, Kiura mining area, Oita Prefecture, Japan. It occurs as aggregates of granular crystals up to 10 μm in diameter and as botryoidal aggregates up to 0.5 mm in diameter, in association with arseniosiderite, and aragonite. The talmessite is white to colorless, transparent, and has a vitreous luster. The unit-cell parameters refined from powder X-ray diffraction patterns are a = 5.905(3), b = 6.989(3), c = 5.567(4) Å, α = 96.99(3), β = 108.97(4), γ = 108.15(4)°, and Z = 1. Electron microprobe analyses gave the empirical formula Ca2.15(Mg0.84Mn0.05Zn0.02Fe0.01Co0.01Ni0.01)∑0.94(AsO4)1.91·2H2O on the basis of total cations = 5 apfu (water content calculated as 2 H2O pfu). It is suggested that the talmessite formed as a secondary mineral derived from löllingite, calcite, and diopside.
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