著者

長瀬 敏郎 石川 志緒利 栗林 貴弘

出版者

一般社団法人 日本鉱物科学会

雑誌

岩石鉱物科学 (ISSN:1345630X)

巻号頁・発行日

vol.47, no.3, pp.127-140, 2018 (Released:2018-11-17)

参考文献数

56

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Nishiki-ishi is a kind of jasper and shows mixed bright red, yellow-brown, green, and black colors. It occurs in Tsugaru region, Aomori Prefecture Japan and has been used for ornaments. Most of the raw stones are usually collected at shingle beaches, and few outcrops of the jasper are found out. Therefore, the occurrence of Nishiki-ishi has not been reported in detail. To elucidate the formation process of Nishiki-ishi, we observed textures of the rocks and minerals by optical and electron microscopes, Raman spectroscopy and analyzed the chemical compositions of minerals by an electron micro-probe analyzer. Nishiki-ishi were collected from two localities: Aoiwa, Nakadomari-machi, Kita-Tsugaru and Tappi-zaki, Sotogahama, Higashi-Tsugaru, Aomori Prefecture, Japan. It mainly consists of mixtures of micro-crystalline and crypto-crystalline quartz, opal-CT and iron-containing minerals. Its colors are caused by iron-containing minerals; hematite (red), celadonite (green), goethite (yellow), siderite (yellow), pyrite (black), and marcasite (black). These iron-containing minerals, which exhibit needle-like or granular forms, are included as fine grains in quartz crystal and fill boundaries among the quartz crystals. The macroscopic structure of Nishiki-ishi is breccia-like or clastic. In the texture, breccia fragments show yellow or red colors, and green and black parts filled up the space between breccia fragments. Yellow-brown and red color parts of Nishiki-ishi have flamboyant and mosaic (jigsaw) textures, which consist of micro-quartz and optically length-slow type spherules of quartz. Black and green color parts are also composed of opal-CT, chalcedony, and micro-quartz. These features are considerable differences of quartz textures between in brecciated fragments and at the matrix among brecciated fragments. Nishiki-ishi was formed by silicification of volcanic rocks during volcanic activity. After the silicified rocks brecciated, quartz and chalcedony precipitated in the breccia.

著者

瀧川 晶

出版者

一般社団法人 日本鉱物科学会

雑誌

岩石鉱物科学 (ISSN:1345630X)

巻号頁・発行日

vol.51, no.1, pp.220225, 2022 (Released:2022-06-18)

参考文献数

68

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Astromineralogy has developed as an interdisciplinary field between astronomy and mineralogy since the discovery of crystalline silicate dust from stellar atmospheres by infrared observations in the late 1990s. Cosmic dust repeatedly forms and is destroyed along with the physical evolution of stars, and thus is a carrier of metallic elements in the galactic material circulation. Minerals found in the solar system and on Earth are observed outside the solar system as well. In addition, presolar grains are the very survivors of circumstellar dust, and are the key to understanding the observed dust and its formation process. Understanding the galactic material circulation through the formation and evolution of cosmic dust requires knowledge not only of astronomy but also of petrology and mineralogy. In this paper, I review the progress of astromineralogy including the author's research and discuss how mineralogy has contributed to the development of astromineralogy.

著者

宮脇 律郎

出版者

一般社団法人 日本鉱物科学会

雑誌

岩石鉱物科学 (ISSN:1345630X)

巻号頁・発行日

vol.43, no.1, pp.11-18, 2014 (Released:2014-03-11)

参考文献数

35

被引用文献数

1

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A rare earth mineral is defined as a mineral containing rare earth elements (REE: Sc, Y and lanthanoids) as essential constituents. So far, more than 280 species of RE minerals, as independent species, have been described after the official IMA-CNMNC approval. The chemical bonds between REE and anions possess largely ionic character and the coordination polyhedra of REE are not regular, but rather distorted, in almost all cases. The REE3+ ions exhibit 7 kinds of coordination number between 6 and 12, among which 8 is the most frequently observed. The coordination numbers of the larger Ce-group REE3+ are similar to those of Ca2+ and Th4+, and are generally higher than those of the smaller Y-group REE3+, which is similar to that of U4+. Isomorphous substitutions are commonly observed between cations having similar ionic radii and coordination numbers. The difference in the cation size between the Y- and Ce-group REE results in different crystal structures, when these structures consist of isolated anionic groups, such as CO32− and PO43−. The crystal structures having infinite frameworks, e.g., chains, sheets and 3-dimensional frameworks of silicate, niobates and others, sometimes accept both of the Y- and Ce-group REE in the spaces between/among the frameworks. The isomorphous substitutions between REE3+ and the other heterovalent cations found in the crystal structures of RE minerals are coupled substitutions with charge compensation mechanisms.

著者

千葉 茂樹 木村 純一

出版者

日本鉱物科学会

雑誌

岩石鉱物科学 (ISSN:1345630X)

巻号頁・発行日

vol.30, no.3, pp.126-156, 2001-05-30

被引用文献数

4 2

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Bandai volcano is located in the southern part of Tohoku-Honshu arc, Japan, and has been active from about 300 ka. Most recently, the volcano erupted in 1888 and the phreatic eruption caused volcanic body collapse and produced huge debris avalanche deposit. Here we present new data of the tephrochronology and volcanic geology of Bandai volcano and discuss its growth history. The tephra-loam association in this area consists of the Hayama and the Mineyama Loam Formations. Sixty-three layers of tephra are recognized in the Mineyama Loam Formation, and seventy-seven layers of tephra in the Hayama Loam Formation. The volcanic activity is classified into seven stages based on tephrochronology: Stage 1: 300 ka≤(presumed age), Stage 2: 300-280 ka, Stage 3: 250-230 ka, Stage 4: 170-85 ka, Stage 5: 75-57 ka, Stage 6: 36-28 ka, Stage 7: 24-0 ka. Pyroxene andesite lavas and tephras are eruptions of Bandai volcano throughout its activity, and more than 13 large avalanche deposits are found in Stages 2, 5, 6, and 7 including 1888 debris avalanche. Modes of eruptions were almost sub-plinian with lava effusions from Stages 2 to 3, whereas sub-plinian was subsequently followed by vulcanian with lava effusions from Stages 5 to 7. Sub-plinian eruptions occurred in the earliest phase of Stages 5, 6, and pumice falls with occasional pumice flows were associated. Stage 4 consists of two eruption types. Large debris avalanches were commonly produced related with the sub-plinian eruption, except for 1888 eruption. Bandai volcano is a complex of at least five stratocones, and resurge of volcanic activity caused collapse of pre-existed volcanic body. This cyclic feature is considered to be the behavior of the volcano.

著者

吉村 俊平

出版者

一般社団法人 日本鉱物科学会

雑誌

岩石鉱物科学 (ISSN:1345630X)

巻号頁・発行日

vol.49, no.2, pp.51-57, 2020 (Released:2020-11-03)

参考文献数

35

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Despite its water-rich nature, silicic magma often erupts calmly to discharge bubble-poor lava without accompanying violent explosion. To allow a water-rich magma to avoid explosion, gas phase that forms as a result of decompressive exsolution needs to escape efficiently to the outside of the magma. However, mechanism of this gas escape has long been unclear, mainly because direct evidence of gas pathways is rarely preserved in natural lava samples. In this paper I show that chlorine-content mapping analysis successfully visualizes the gas pathways hidden in groundmass glass. This chlorine mapping analysis was developed based on an idea that chlorine diffusivity in rhyolitic melt is so low that chlorine heterogeneity formed through degassing processes may survive for a long time without being homogenized. Timescales of degassing processes are estimated by applying a diffusion model to the observed heterogeneity. Results of my recent chlorine diffusion experiments are also presented, as the chlorine diffusivity is the key for interpreting the observed heterogeneity.

著者

鹿園 直建 原田 広康 池田 則生 柏木 洋彦

出版者

一般社団法人 日本鉱物科学会

雑誌

岩石鉱物科学 (ISSN:1345630X)

巻号頁・発行日

vol.38, no.5, pp.149-160, 2009 (Released:2009-11-26)

参考文献数

20

被引用文献数

3 3

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Dissolution kinetics model calculations were performed for the interaction between three types of basaltic rocks in Japan (Fuji and Hachijyojima fresh basalts and Kitamatsuura altered basalt) and groundwater injected CO2. Dissolution rates of the basalts experimentally determined by the authors (Shikazono et al., 2008) and database of dissolution rate constants of silicate minerals in the basaltic rocks in PATHARC (Talman et al., 2000) were used for the calculations. The results of calculations indicate that most of dissolved carbon in groundwater injected CO2 can be fixed as carbonates in long-term period. The efficiency of carbon fixation is in an order, Hachijyojima>Fuji>Kitamatsuura. But the efficiency is not so different for three basaltic rocks in the fixation of carbon in underground sequestration of CO2. It is inferred that mineral trapping of CO2 by carbonates in basalt aquifer is useful for the long-term fixation of carbon in underground sequestration of CO2.

著者

坂野 靖行

出版者

一般社団法人 日本鉱物科学会

雑誌

岩石鉱物科学 (ISSN:1345630X)

巻号頁・発行日

pp.210511, (Released:2021-11-10)

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Monazite in a granite pegmatite from the Ishikawa district, Fukushima Prefecture, Japan has been examined in terms of U, Th, Pb, and rare earth element (REE) chemistry by electron microprobe analysis. Oscillatory and sector zoning were distinguished on the basis of back-scattered electron images. An averaged empirical formula was (Ce0.383Nd0.204La0.136Y0.062Sm0.061Pr0.050Gd0.040Dy0.014Er0.002Th0.046U0.005Ca0.011)∑1.014(P0.952Si0.040)∑0.992O4. Compositional variations suggest that the (Th + U) contents are controlled mainly by the coupled substitution (Th, U)+ Si = REE + P. Analytical data for clear portions of the monazite crystal were arrayed linearly on the PbO-ThO2* (ThO2 plus the equivalent of UO2) diagram and formed a single isochron for a CHIME age of 103 ± 26 Ma (2σ) that is in accord with previously reported radiometric ages for the granitic rocks in the Ishikawa district.

出版者

一般社団法人 日本鉱物科学会

雑誌

岩石鉱物科学 (ISSN:1345630X)

巻号頁・発行日

vol.49, no.4, pp.148, 2021

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<p>黒田吉益先生のご逝去を悼む</p>

出版者

一般社団法人 日本鉱物科学会

雑誌

岩石鉱物科学 (ISSN:1345630X)

巻号頁・発行日

vol.49, no.4, pp.148, 2021 (Released:2021-03-11)

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黒田吉益先生のご逝去を悼む

著者

荒井 章司

出版者

一般社団法人 日本鉱物科学会

雑誌

岩石鉱物科学 (ISSN:1345630X)

巻号頁・発行日

vol.41, no.6, pp.247-256, 2012 (Released:2012-12-29)

参考文献数

56

被引用文献数

4 4

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Podiform chromitites have been interpreted as cumulates formed via melt/harzburgite reaction and subsequent melt mixing within the upper mantle. Recent finding of ultrahigh-pressure (UHP) minerals such as diamond from some podiform chromitites has, however, seriously required us to reconsider the whole framework of podifrom chromitite genesis. The UHP podiform chromitites are characterized by presence of frequent silicate lamellae in chromian spinel and only PGE (platinum-group elements) alloys as platinum-group minerals. The UHP chromitites were possibly formed by deep recycling of the ordinary low-pressure podiform chromitites. Diamonds could be formed by reduction of CO2 metasomatically supplied to chromian spinel in advance. Silicate lamellae in chromian spinel of UHP chromitites were possibly derived from primary silicate inclusions (pyroxenes, pargasite and Na phlogopite), commonly found in the low-pressure chromitite. They were decomposed/partially melted and resolved in high-pressure chromian spinel during compression/heating during downward transportation, and were exsolved as silicate lamellae on decompression/cooling during uprising. PGE sulfides commonly found in the low-pressure chromitite may have been decomposed to PGE alloys and sulfur-rich melt/fluid that were removed outside.   We should systematically re-examine all podiform chromitites that have been ever documented, but our preliminary examination indicates that both concordant and discordant chromitites from Oman ophiolite are of low-pressure origin, containing primary pargasite inclusions in chromian spinel. More thorough characterization of the UHP chromitite may enable us to place constraints on the style of mantle convection that provided the MORB source possibly comprising the UHP chromitite. Possible presence of ringwoodite as one of UHP minerals in chromitite may favor the two-layer mantle convection for supplying the source mantle that formed the oceanic lithosphere.

著者

大藤 弘明

出版者

一般社団法人 日本鉱物科学会

雑誌

岩石鉱物科学 (ISSN:1345630X)

巻号頁・発行日

vol.41, no.1, pp.12-18, 2012 (Released:2012-03-10)

参考文献数

23

被引用文献数

1 1

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The 3D packing structures of microcrystals in framboidal pyrite have been investigated by morphological observations and crystallographic orientation analyses using the EBSD technique to understand its self-organization process. The packing structures are basically classified into three types: (i) face-centered cubic (fcc), (ii) icosahedral and (iii) random packings. The orientation analyses on many ordered (fcc) framboids revealed that about a half of the microcrystals in a framboid involve high-angle (~ 90°) misorientation. This means that even in morphologically highly ordered framboids, the crystallographic orientations of microcrystals are not uniform, suggesting that the self-organization process of framboidal microcrystals is not crystallographically controlled. We propose a three-step model for the self-organization: (1) simultaneous nucleation of monodispersive pyrite microcrystals in a fixed volume (from precursor FeS), (2) aggregation of the randomly oriented microcrystals driven by surface forces and the reduction in total surface energy associated with both the individual microcrystals and the whole aggregate, resulting in the formation of the framboidal texture, and 3) reorientation of the microcrystals driven by further reduction in surface energy associated with the grain boundaries.

著者

横山 光 八幡 正弘 岡村 聡 西戸 裕嗣

出版者

一般社団法人 日本鉱物科学会

雑誌

岩石鉱物科学 (ISSN:1345630X)

巻号頁・発行日

vol.32, no.2, pp.80-95, 2003 (Released:2008-04-21)

参考文献数

26

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Late Pliocene-Pleistocene Akaigawa Caldera, 6-7 km in diameter, is located in southwest Hokkaido. It mainly consists of felsic caldera-forming welded tuffs, somma lavas, and lacustrine deposits in order of decreasing age. Caldera-forming pyroclastic flows of the Nagasawa Volcanics were erupted at the southwestern caldera rim and are characterized by high SiO2 content (76-79%). Contrary to this, the subsequent somma lavas were erupted from multiple vents along ring fractures and have variable SiO2 contents ranging from basaltic andesite to dacite (56.6-66.7%).The whole rock K-Ar age of the lower member of the welded tuffs is 2.06±0.57, whereas the age of the middle member 1.62±0.14 Ma. The Maruyama Lava and the Daikokuyama Lava from the somma lavas give ages of 1.65±0.07 Ma and 1.55±0.06 Ma, respectively. The age of the middle member of the welded tuffs coincides within measurement errors with ages determined for the somma lavas. The age and geological structures of the lower member of the welded tuffs suggest that the pre-Akaigawa, outer Yoichigawa Caldera formation began before 2 Ma. On the basis of petrography and geochemistry, the somma lavas are divided into three units; the eastern somma lavas, the western somma lavas, and the post-caldera central cone. The lithologies of eastern somma lavas range from olivine basaltic andesite to andesite, and the western somma lavas range from quartz andesite to dacite, indicating a similar geochemical trend to that of the eastern somma lavas. The post-caldera central cone is composed of andesite to dacite, and has a different geochemical signature from that of the somma lavas. The volcanic structure, topography, eruption volume, and petrography indicate that the Akaigawa Caldera-collapse took place after eruptions of both welded tuffs and somma lavas, and that the western side of the caldera is characterized by a higher eruption rate of felsic to intermediate magma and more extensive subsidence compared with the eastern side. This may indicate the existence of a heterogeneous magma chamber beneath the Akaigawa Caldera.

著者

柵山 徹也

出版者

一般社団法人 日本鉱物科学会

雑誌

岩石鉱物科学 (ISSN:1345630X)

巻号頁・発行日

pp.120611a, (Released:2013-01-24)

著者

山中 高光

出版者

一般社団法人 日本鉱物科学会

雑誌

岩石鉱物科学 (ISSN:1345630X)

巻号頁・発行日

vol.32, no.3, pp.109-111, 2003-05-30

著者

五十公野 裕也 中島 和夫

出版者

一般社団法人 日本鉱物科学会

雑誌

岩石鉱物科学 (ISSN:1345630X)

巻号頁・発行日

vol.44, no.4, pp.205-209, 2015 (Released:2015-08-30)

参考文献数

14

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Bi minerals have been discovered from the Fukueison mine, situated in the Uetsu region, Tsuruoka City, Yamagata Prefecture, Japan. Bi minerals occur in quartz veins which consist of chalcopyrite, pyrite and chlorite, accompanied by minor molybdenite, sphalerite and arsenopyrite, hosted in the Nishitagawa granodiorite. Bi minerals are composed of bismuthinite as a major constituent and native Bi, Bi-sulfosalts (krupkaite, cosalite and galenobismutite) and Bi-Te-S minerals (tetradymite, joséite-A, joséite-B and ingodite) as minor constituents. From the paragenesis and texture of Bi minerals, these minerals might have been formed by a change of fS2 and fTe2 conditions. Comparing to other Bi-bearing Mo deposits, Inner Zone of Southwest Japan, it is considered that Bi is closely related with Cu mineralization.

著者

平野 伸夫 竹之下 愛 土屋 範芳

出版者

一般社団法人 日本鉱物科学会

雑誌

岩石鉱物科学 (ISSN:1345630X)

巻号頁・発行日

vol.38, no.5, pp.198-207, 2009-09-30

参考文献数

28

被引用文献数

1 2

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&nbsp;&nbsp;Carbonate hot spring is a natural chemical reaction field for understanding CO₂ geological sequestration as a natural analogue. Natural analogue studies are particularly important to understand the kinetics of mineral precipitation which has potential difficulties in experimental investigations. Carbonate sinter is frequently formed in and around carbonate hot spring, which can be suitable to elucidate mechanisms of carbonate precipitation associated with flushing CO₂.<br> &nbsp;&nbsp;Oku-Okuhachikuro hot spring, located in Kosaka town, Akita Prefecture, NE Japan, is an artificial hot spring after drilling of exploration for the Kuroko-deposits, and it is still active where carbonate sinter has still been forming continuously for more than thirty years after drilling. The temperature of spring water is 44 &deg;C and water pH is 6.2, with discharge rate of 0.08 m³/min. The average chemical compositions of sinter correspond about 80 wt% CaCO₃, and 4 wt% Fe₂O₃, associated with minor (<1 wt% each) SiO₂, MnO, MgO, Na₂O and K₂O. Carbonate sinter is mainly composed of aragonite with a small amount of calcite; an intimate occurrence of these two forms of CaCO₃ is the most characteristic feature of this locality. However, mineral assemblage, texture and structure of carbonate sinter are different in relation to the distance from the blowout point. Near the blowout point, the sinter is well solidified and shows laminar structure having both of calcite and aragonite. Thickness of Ca-rich laminar ranges from 20 to 150 &mu;m and Fe-rich one is from 10 to 80 &mu;m. Calcite and aragonite assemblage is mainly observed in Ca-rich layer. The Fe-rich layer, however, is composed only of aragonite. The sinter along downstream becomes porous and is monomineralic having aragonite as CaCO₃. The observed relations on the special distribution of aragonite/calcite and the possible stability relations of these phases through EPMA and TG-DTA analyses suggest an importance of minor elements (Fe, <i>etc.</i>) in the precipitation of metastable carbonates: this possible effect of the precipitation of metastable phases should be taken into account in the consideration of geochemical processes of CO₂ mineral trapping.<br>

著者

牧野 州明

出版者

一般社団法人 日本鉱物科学会

雑誌

岩石鉱物科学 (ISSN:1345630X)

巻号頁・発行日

vol.29, no.2, pp.45-51, 2000 (Released:2008-08-30)

参考文献数

22

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Characteristic structure of Cl-amphibole is reviewed, and its application to chemical zoned amphibole from the Ramnes cauldron is summarized.Large ionic radius of Cl− brings geometrical and chemical effects to the amphibole structure. In the Cl-amphibole, the double chain is significantly deformed to fit expanded octahedral strips, which is achieved by substitution of IVAl for Si (geometrical constraint). The Cl− projects toward the A site and there is a interaction between Cl− and cations in the A site (A site constraint). The short range order of Fe2+-Cl− is observed in Cl-amphibole (chemical constraint). These constraints simultaneously control the Cl− content in amphibole and imply that Cl− substitutes for OH− only in the ferro-paragasite or ferro-hastingsite component. Based on these structural considerations on Cl-amphibole, Cl− variations in the zoned amphibole from the Ramnes cauldron were interpreted. The zoning were developed under different fluid conditions in chemistry and temperature.

著者

松原 聰

出版者

一般社団法人 日本鉱物科学会

雑誌

岩石鉱物科学 (ISSN:1345630X)

巻号頁・発行日

vol.48, no.2, pp.87-88, 2019 (Released:2019-06-05)

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日本新産鉱物情報(2017年)以降,2018年12月末までに確認された日本産新鉱物および新産鉱物,その他について紹介する.太字は少なくとも化学的,結晶学的性質が明らかにされたもので,信頼度が高い.

著者

亀井 淳志 内藤 一樹 高村 早弥香 加々島 慎一 奥澤 康一 関 陽児 渡部 芳夫

出版者

一般社団法人 日本鉱物科学会

雑誌

岩石鉱物科学 (ISSN:1345630X)

巻号頁・発行日

pp.131211, (Released:2015-04-28)

被引用文献数

1

著者

佐藤 景 石渡 明

出版者

一般社団法人 日本鉱物科学会

雑誌

岩石鉱物科学 (ISSN:1345630X)

巻号頁・発行日

vol.44, no.3, pp.155-170, 2015 (Released:2015-06-27)

参考文献数

52

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Ishikoshi Andesite is the Middle Miocene, amphibole-bearing, two pyroxene andesite lava flow located in the forearc area of the Northeast Japan arc, which covers the area of 8 km EW and 7 km NS and has the thickness of >180 m. In this study it is divided into peripheral lava (PL) and central lava (CL), which are distributed in the peripheral and central parts of the volcanic edifice, respectively. PL bears groundmass pigeonite or shows higher FeO*/MgO trend with fractionation and CL does not bear pigeonite and lower FeO*/MgO trend, therefore PL is tholeiitic and CL is calc-alkaline. PL shows petrological features that are compatible with crystallization differentiation. CL has several features that suggest magma mixing such as non-equilibrium plagioclase phenocrysts, but evidences for magma mixing are not robust. In comparison to similar lava flows, PL and CL seem to form a composite lava flow because clear geological boundary between PL and CL cannot be observed and FeO*/MgO ratio of CL tend to be higher in the marginal portion. We also find that two-pyroxene equilibrium temperature of CL (760-850 ℃)is lower than that of PL (970-990 ℃). CL should have been too viscous at this temperature (>1010 Pa·s in anhydrous state) to form a dike, thus it should have effused through the vent which PL formed to be composite lava flow with PL. Ishikoshi Andesite has columnar joints rather than platy joints. In comparison to other lava flows which have platy joints in Japan, it is possible that less anisotropic crystals, low eruption temperature (high viscosity) and/or large phenocryst size have prevented Ishikoshi Andesite from formation of foliation along which platy joints develop in the lava.