著者

草薙 忠明

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.13, no.58-59, pp.95-100, 1963-04-30 (Released:2009-06-12)

参考文献数

9

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The Ashio Mine is composed mainly of the rhyolitic comlex and the Palaeozoic formation. The ore deposits occur both in them as vein and "Kajika" deposits.Four hypogene mineral zones, a central Sn-W-Bi-Cu zone, an intermediate Cu-As-Zn zone, a marginal Zn-Pb-Cu-As zone and a barren zone are quite distinguished in the rhyolitic complex as Takeshi NAKAMURA (1961) clarified them.Hypogene mineralization in the Palaeozoic formation and in the southern part of the rhyolitic complex adjacent to the Palaeozoic formation is very similar to that in the rhyolitic complex, but large amounts of ealier pyrrhotite and marmatite occur in the Palaeozoic formation. In general, three mineral zones, a Fe-Zn-As zone, a Cu zone and a silicified and barren zone are distinguished remarkably from the foot-wall side to the hanging-wall side of the "Kajika" deposits in the Palaeozoics.The mineralizations both in the rhyolitic complex and the Palaeozoics are considered to be taken place at the same time after the rhyolitic complex extruded.The features of the high-temperature tin and tungsten minerals are associated with the low-temperature copper, lead, zinc and other minerals show the telescoped character of the Ashio deposits. The ore deposits at the Ashio Mine classified as the epithermal deposit are considered to be formed under the subvolcanic environment caused by the vocanism of the Ashio rhyolitic complex.

著者

大町 北一郎

出版者

資源地質学会

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.3, no.9, pp.181-186, 1953-10-25 (Released:2009-06-12)

参考文献数

14

著者

田口 幸洋 広渡 文利 吉川 謙造

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.26, no.138, pp.263-271, 1976-10-30 (Released:2009-12-14)

参考文献数

15

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The Fuke mine, situated at about 10 km north of Okuchi city in Kagoshima Prefecture, is one of the gold-silver ore deposits of the epithermal vein type in the Green-tuff region. The ore deposit is considered to be an intermediate type between the gold-silver vein and the base metal vein.The high grade ore in the mine is named "Tozi-kin" in which can be visually recognized the part where fine-grained golds are concentrated. As for the electrum in this ore, mode of occurrence and chemical composition have been investigated by a microscope and EPMA. The results are as follows : 1. The Tozi-kin ore often shows a characteristic banded arrangement from the wall rock to the inner of the ore; Fe-Mg chlorite, drusy quartz with pyrite and hematite, fine-grained quartz with banded sulfides and electrum, and green clay mainly composed of chlorite-saponite mixed-layer.2. Paragenetic sequence of vein minerals may be divided into four stages; First stage: Drusy quartz accompanied by pyrite and hematite. Second stage: Fine-grained quartz characterized by sulfides and electrum. Third stage: Altered minerals. Fourth stage: Barren quartz associated with calcite. 3. Observed ore minerals are electrum, galena, sphalerite, chalcopyrite, pyrite, hematite, hessite, and an unkown Ag-Au telluride.4. Electrum precipitated after the precipitation of sulfides in the second stage.5. The electrum filling intergranular cavities of quartz is irregular and angular in shape, whereas that in sulfides varies from granular to cylindrical, and often amoebic.6. The grain size of electrum is generally less than 50 microns in diameter, but it attains 200 microns in some cases.7. The chemical composition of electrum from the Fuke-honpi vein shows a very little fluctuation among grains as well as in a grain, with an average chemical composition Ag 19.1 wt.%, Au 80.6 wt.%.Some of these properties of electrum such as the homogenity of composition and the relatively coarse grains, are considerably different from those of electrum in the Kuroko ore.

著者

石原 舜三 木村 幹 大田 浩二 佐藤 壮郎

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.35, no.192, pp.295-298, 1985-08-30 (Released:2009-12-14)

参考文献数

14

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Twenty-four granitoids from three magnetite-series granitic terranes and three ilmenite-series granitic terranes were analyzed for gold by the neutron activation method. The gold values of the magnetite-series granitoids range from 0.4 to 7.1 ppb and the average is 4.3 ppb, while those of the ilmenite-series granitoids vary from 0.4 to 4.8 ppb and the average is 2.5 ppb. The higher values of the magnetite-series granitoids than the ilmenite-series ones may be attributed to the presence of rock-forming magnetite in the former series. The gold values appear to increase with the in-creasing of silica contents within the range of 61-76%. Magnetite-series granitic terranes are considered to be more favarable basement than ilmenite-series ones for Neogene gold mineralization of the Green Tuff region.

著者

佐々木 昭 佐藤 和郎 George L. Cumming

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.32, no.176, pp.457-474, 1982-12-15 (Released:2009-06-12)

参考文献数

48

---

The metallic mineralization in the Japanese islands can be divided into three groups in view of the ore lead isotope systematics.(1) The Paleozoic to Mesozoic stratiform (Besshi-type) mineralization is composed of cupriferous iron sulfide ores in which lead is usually a minor constituent (to the level of 10 1-10 2 ppm). The leads are isotopically variable, being consistently low in both 207Pb/ 204Pb and 208Pb/ 208Pb ratios as compared to the lead in the "major (conformable) lead orebodies" of similar ages.(2) The pre-Neogene mineralization excluding the Besshi-type deposits is mostly related to Cretaceous to Paleogene granitoids. Galena is fairly common and forms sizable orebodies in a few skarn-type deposits. Lead isotopic composition is more or less variable regionally, and even locally in some cases, all being, however, low in 206Pb/ 204Pb and high in 208Pb/ 204Pb ratio in comparison with the conformable ore leads.(3) The Neogene mineralization is represented by the kuroko-and related vein-type mineralization of middle Miocene age, carrying abundant lead as one of the major ore metals. The leads are isotopically rather uniform with consistently low 206Pb/ 204Pb and high 208Pb/ 204Pb ratio as compared to the major lead ore system; 43 samples from 30 localities give average 208Pb/ 204Pb 207Pb/ 204Pb and 208Pb/ 204Pb ratios of 18.471±. 108 (2σ), 15.609±.036, and 38.677±.220, respectively. A remarkably consistent isotopic composition close to this average is observed in the kuroko ores from an extensive area of northeast Japan.The Besshi-type ore leads except for those of the Mesozoic Taro deposit show an isotopic pattern similar to that of the ocean volcanic leads, strongly suggesting that the major evolutionary environment of these leads has been in the oceanic mantle. The Taro leads show isotopic features close to the major lead ore system and, in this respect, are unique among Japanese ore leads.The leads of the pre-Neogene and Neogene mineralizations may be identified as crustal lead with respect to their main evolutionary environments. The 207Pb/ 204Pb and 208Pb/ 204Pb ratios of the pre-Neogene leads exhibit a trend in which the relatively high values of these ratios occur in the area where the related granitoids have relatively high initial 87Sr/86Srr ratios; some Neogene leads seem to follow the same trend. The presence of a relatively old and thick continental crust in the source region of these leads can be deduced.The available isotopic data for the oceanic sediment lead occurring closer to the Japanese islands (samples near the Mariana volcanic arc and those from the Ryukyu Trench) apparently deviate from the major spectrum of the Pacific sediments data and plot closer to the data for the Japanese Neogene and pre-Neogene ore leads which may approximate the average of Japanese crustal leads. A relatively 208Pb-impoverished and 208Pb-enriched character indicates that the crustal lead around the Japanese islands has been strongly influenced by the lead evolved in the lower continental crust.

著者

堀越 義一

出版者

資源地質学会

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.8, no.28, pp.101-106, 1958-04-30 (Released:2009-06-12)

著者

苣木 淺彦 長谷川 修三

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.2, no.6, pp.185-196, 1952-12-25 (Released:2009-06-12)

参考文献数

49

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The Hayama Mine is situated on the Abiikuma Plateau about 15 kilometers to the southeast of Fukushima City. The district is composed mostly of hornblende biotite granodiorite. However, some hornfels and ultra-basic rocks, such as dunite and diallagite, are present in the form of a roof-pendant. The nickel-bearing minerals, such as niccolite, gersdorffite, pentlandite and nickeliferous pyrrhotite etc., occur as fine grains in the forsterite aggregates, which form a vein-like body in dunite. The forsterite rock is also cut by remarkable black veinlets, composed of the acicular or fibrous crystals of ludwigite. Ludwigite is known to be produced by the chemical reaction of boron- and iron-bearing emanations from granitic magma on some magnesium-bearing rocks such as dolomite and magnesite. Under the microscope, the nickel minerals generally appear in pure crystals, filling up the interstices between the forsterite grains. The niccolite, is rarely rimmed with gersdorffite. Ludwigite is always accompanied by magnetite and chromite which are thought to have been derived from the ultra-basic rock.The paragenesis of nickel minerals-forsterite-ludwigite-chromite is very critical in the interpretation of the ore genesis. This deposit must be studied from two viewpoints, one from magmatic differentation and the other from contact metasomatism.

著者

宮沢 俊彌

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.4, no.13, pp.139-146, 1954-10-10 (Released:2009-06-12)

参考文献数

16

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There are two known modes of occurrence of hematite and magnetite at the Chichibu Mine, Saitama Prefecture.One type of hematite occurs as the earliest ore mineral. This type of hematite has been largely transformed into magnetite, especially at the time of formation of earlier pyrite. The other type of hematite is only found within the zone of oxidation product of granular magnetite.As for magnetite, one type occurs as granular aggregates or well-shaped crystals. Most of them may be of primary origin and may have crystallized out as magnetite during the earliest stage of metallization, but some of them are closely related with the formation of platy magnetite. The other type shows a platy form and may largely be the reduction (hypogene secondary) product of primary hematite.

著者

スミルノフ V.I. ボロダエフ Iu.S. スタロスチン V.I.

出版者

資源地質学会

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.18, no.91, pp.284-291, 1968

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日本の硫化鉄鉱鉱床<SUP>*1</SUP>の多くは,アルプス地向斜発展期初期段階のものである中新世のスピライトーケラトフフイア岩系の岩石帯に集中している.この種の鉱床の鉱体は,火山砕屑岩層に覆蔽された流紋岩質層の近辺に賦存し,累帯構造を示している.下位の熱水性変質作用を受けている流紋岩中には,交代成微脈―鉱染状硫化物鉱石(珪鉱)が発達している.その上位には塊状の硫化鉄鉱鉱石(黄鉱)が分布している.そしてさらに,海成の成層火山砕屑岩に整合的に覆蔽された高品位多金属鉱(黒鉱―чёрная руда,black ore)が,その上位に分布している.この鉱床は,火山源堆積作用の複合生成物と思われる.すなわち,鉱体下位のものは流紋岩に対する熱水溶液の作用によつて生成し,上位のものは中新世の海底にその熱水溶液が運んできた物質が沈殿して生成したものと思われる.<BR>1940年代になつて,A.ザヴァリツキーはウラルの硫化鉄鉱鉱床について新しい火山源生成説を提起したが,彼は,第三紀火山作用と結びつけた日本の「黒鉱」に関する日本の地質学者たちの考え方(木下亀城,1931)をその中にとり入れ支持していた.しかし硫化鉄鉱鉱床の生成条件に関する考え方が変つてきた現在,日本の硫化鉄鉱鉱床の地質に関するデータは,その火山源熱水―堆積性起源説(Theory of volcanogenic hydrothermal-sedimentary origin)の検討に基本的な支えとなり得るものである.そのために,日本のデータがソ連の地質学者の大きな関心を呼んでいるわけである.<BR>本論文を執筆するに当つて筆老らは次のように分担した.すなわち,1966年秋に日本の代表的な「黒鉱」鉱床を訪れて,研究試料を得てきたV.I.スミルノフは,地質の記載とその他のすべてのデータの全般的な総括(スミルノフ,1967)を行ない,Iu.S.ボロダエフは鉱石試料の顕微鏡的研究結果についてまとめ,V.I.スタロスチンはその試料の物理的性質の研究を行ない,そのデータを提供した.<BR>本論文の執筆は,東京大学の渡辺武男教授と立見辰雄教授,東北大学の竹内常彦教授,その他のきわめて熟達した著名な日本の鉱山地質学者との会合で,大いに刺激された結果である.また,同和鉱業株式会社社長新井友蔵博士とその補佐役の方々から,日本の硫化鉄鉱鉱床の巡検に積極的な協力と援助を受けた.これらすべての方々,および本論文を校閲して下さつたT.N.シャドルンとG.F.ヤユヴレフの両氏に厚く感謝申し上げる.<BR>著者はまた,日本の鉱石試料から得た硫化鉱物中の硫黄同位元素の分析を早く終了するために,V.I.ヴィノグラードフの高配を得た.<BR>当該鉱床の地質を説明する図葉は,日本の鉱山地質学者の資料から借用したが,遺憾ながら原図に明記してないため,その人々の名を示すことができなかつた.

著者

三野 英彦

出版者

資源地質学会

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.12, no.51, pp.46-56, 1962

著者

バクヒット F.S.

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.37, no.201, pp.29-43, 1987-03-31 (Released:2009-06-12)

参考文献数

33

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鉱脈型あるいは割目充填型ウラン鉱化作用の母岩として最も適している花崗岩の決定法を調べた.対象としたのは,エジプトの東砂漠に分布する赤色花崗岩である.ウラン鉱化作用に最も適した赤色花崗岩は,珪酸分が高く,ナトリウムとカリウムに富んでおり,鉄,マグネシウム,カルシウムが少いことが明らかとなった.また,ウラン鉱化作用に適した地質構造は,主要断層に平行な,あるいは隆起帯の下盤に沿う副次的な断層ないし割目である.花崗岩体の縁からはるかに離れたところには,ウラン鉱床は存在しない.

著者

石原 舜三

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.27, no.145, pp.293-305, 1977-10-30 (Released:2010-03-04)

参考文献数

47

被引用文献数

30

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表題の2組の花崗岩類について,主として鏡下観察結果から構成鉱物の特徴が記載され,分類の基準・両者の分布・成因・鉱化作用との関連性などがのべられた.2組の花崗岩類は一般の鏡下観察(100×)で磁鉄鉱が認められるか否かの点で分類され,磁鉄鉱系花崗岩類は0.1―2容量%の磁鉄鉱とごく少量のチタン鉄鉱を有し,チタン鉄鉱系花崗岩類は0.1容量%以下のチタン鉄鉱を伴うにすぎない.すなわち,両者は苦鉄質珪酸塩鉱物とFe-Ti酸化鉱物の量比において著しく異なり,チタン鉄鉱系花崗岩類はFe-Ti酸化鉱物に欠ける系列とみなしてよい.このFe-Ti酸化鉱物に欠ける事実から,チタン鉄鉱系花崗岩類が磁鉄鉱系花崗岩類より低い酸素フュガシテイの条件下で生成されたものと推論された.このように考えると,2組の花崗岩類にそれぞれ特徴的に認められる他の苦鉄鉱物や硫化鉱物の組合せが説明し易い.両者の酸素フュガシティを定量的に推定する共通の鉱物組合せは得られていないが,黒雲母のFe+3/Fe+3+Fe+2比から両者の境界はほぼNi-NiOバッファー付近と考えられた.花崗岩類の生成時の酸素フュガシティを規制する要因としては花崗岩質マグマの発生から固結に至る過程における炭質物によるバッファーが重視され,H2Oの解離とH2の逸散は磁鉄鉱系花崗岩類の一部について考慮された.磁鉄鉱系花崗岩類は炭質物が存在しない深所起源であり,チタン鉄鉱系花崗岩類は炭質物を伴う大陸地殻起源であろうと考えられた.花崗岩類中かその近傍に産出する鉱床においては花崗岩類にみられる性質が継続して認められ,たとえばポーフィリーカッパー鉱床では磁鉄鉱系花崗岩類と共通の鉱物組合せが産出する.2組の花崗岩類の性質はマグマ期末期から後マグマ期の一部に及んでおり,花崗岩類に密接な鉱床探査では両者を識別することが重要である.スズ-鉄マンガン重石鉱床がチタン鉄鉱系花崗岩類と密接な経験則から,環太平洋地域の西側では磁鉄鉱系花崗岩類に乏しいことが予想され,このことが沿海州―中国大陸南東部―マレ―半島に至る中生代花崗岩類にポーフィリーカッパー鉱床が発見されない一因と考えられた.

著者

志保井 利夫

出版者

資源地質学会

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.3, no.8, pp.119-124, 1953-07-25 (Released:2009-06-12)

著者

宮久 三千年

出版者

資源地質学会

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.12, no.56, pp.317-323, 1962

被引用文献数

1

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The contact metasomatic and the vein-type ore deposits of the Shin-Kiura tin mine have been worked since old times for tin, silver, arsenic and copper. These are characterized by complex mineralization at a wide range of temperature related to the Tertiary granitic intrusion. Recently, lollingite-cassiterite-quartz-wollastonite vein-like deposits, containing native gold, native bismuth and tellurobismuthite, have been found in the Uriya-Kaneko adit of this mine.<BR>In this paper, mineragraphy of the Au-Te-Bi-As ore is presented, and genesis of the similar mineralizations in Japan is discussed.

著者

宮久 三千年 原田 進造 石橋 澄 渋谷 五郎 本村 慶信

出版者

資源地質学会

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.25, no.133, pp.347-357, 1975

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In this paper, the paragenesis of minerals in the Hoei mine is presented with some remarks on the mineralogical properties of kutnahorite.<BR>The Ichigo (no.1) ore body of the Hoei mine is a massive deposit of Sn, Zn and iron sulfide formed by replacement of the Silurian limestone bed. From this ore body, there have been found various kinds of ore and gangue minerals such as: garnet, clinopyroxene, axinite, tourmaline, vesuvianite, quartz, pyrrhotite, chalcopyrite, arsenopyrite, pyrite, marcasite, sphalerite, galena, native bismuth, herzenbergite, franckeite, jamesonite, cassiterite, stannite, malayaite, fluorite, sericite and carbonate minerals. The species of carbonate minerals are ferromanganoan dolomite, magnesian kutnahorite, kutnahorite, calcian rhodochrosite, ferroan magnesite and manganoan calcite, and they have been crystallized at the later stage of mineralization in this mine.<BR>The kutnahorite in this mine is white, yellow or pinkish in color, and platy or leaf-like in external shape, reaching to 5 cm in maximum length. Its specific gravity ranges from 2.98 to 3.18 by picnometer method. Optically negative, and some examples of refractive indices are &omega;=1.717-1.731, &epsilon;=1.524-1.529. Unit cell constants, a<SUB>0</SUB> = 4.861-4.869 &Aring;, c<SUB>0</SUB>=16.24-16.37 &Aring;. The range of chemical composition of kutnahorite is fairly wide, as shown in Table 4 and 5.<BR>Judging from the mode of occurence, microscopic observations and the compositional changes detected by EPMA, the crystallization sequence of the carbonate minerals is suggested as follows : dolomite-ferromanganoan dolomite-magnesian kutnahorite-kutnahorite-calcian rhodochrosite-manganoan calcite.

著者

広渡 文利 宮久 三千年

出版者

資源地質学会

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.5, no.16, pp.95-101, 1955

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Jacobsite, with chemical composition MnFe<SUB>2</SUB>O<SUB>4</SUB>, belonging to magnetite series of spinel group, has been found in the manganese deposits from the Kiuragi Mine, about 15 kilometers west of Saga-City, Kyushu, Japan. This mineral is fine-grained and in tephroite ores associated with rhodonite, spessartine, rhodochrosite and a small amount of penwithite. It shows the following characters;<BR>Colour is magnetite-like iron black with metallic luster. Streak, blackish brown. Strongly magnetic. Hardness, 6&plusmn; In thin section this mineral is opaque, usually associated with galaxite which shows close similarity in crystal structure. In the polished section it is greyish white with olive tint. Standard etch reactions are negative except that of HCl(conc.)+SnCL<SUB>2</SUB>.<BR>Its X-ray powder pattern is in very close agreement with those of jacobsite from Jacobsberg and artificial MnFe<SUB>2</SUB>O<SUB>4</SUB>. Analysed specimens contain a small amount of galaxite (5.46% wt.). Analytical results are as follows; SiO<SUB>2</SUB> tr., Fe<SUB>2</SUB>O<SUB>3</SUB> 56.19, MnO 29.34, MgO 0.10, CaO 0.13, TiO<SUB>2</SUB> 3.37, AL<SUB>2</SUB>O<SUB>3</SUB> 11.62, BaO none, total 100.75. After deducing MnAL<SUB>2</SUB>O<SUB>4</SUB> for galaxite as impurities, the chemical formula can be written as (Mn, Fe<SUP>II</SUP>, Ca, Mg)<SUB>0.990</SUB> (Fe<SUP>II</SUP>I, Al, Ti)<SUB>1.950</SUB>O<SUB>4.000</SUB>. A precise determination of the lattice dimension by the extrapolation-method gave 8.452&plusmn;0.004A.

著者

宮久 三千年 鹿島 愛彦

出版者

資源地質学会

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.17, no.84, pp.214-227, 1967

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Dolomite deposits of western Shikoku are distributed in some definite stratigraphic and geotectonic zone. They are classified into the following group.<BR>1) Siliceous dolomite deposits of the northern zone of upper Carboniferous in age. These deposits are associated with red tuff, red chert, and other clastic sediments of volcanic materials.<BR>2) Some workable dolomite deposits of the southern zone of lower Triassic Uonashi formation, independent of volcanic activities.<BR>Chief factors of the formation of dolomite are temperature, pH, Eh and concentration of Mg-ion in the sea-water of geosynclinal basin. These factors are related to some paleogeographical environments, such as submarine volcanism (Northern zone) and development of shallow sedimentary basin of nearshore line (Southern zone).<BR>Chemical compositions of mineral dolomites, mechanism of dolomitization, deformation and recrystallization of ores, and relation of dolomite bed to other submarine sedimentary ore deposits are also discussed in this paper.

著者

地質調査所 原子燃料公社

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.14, no.63, pp.1-10, 1964-02-29 (Released:2009-06-12)

参考文献数

12

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The prospecting for nuclear raw material resources in our country was undertaken in 1954 by the Geological Survey of Japan. Based upon the geological consideration, the prospecting operations were carried out in the so-called "massif" region consisting mainly of granites. The first discovery of uranium mineralization in sedimentary rocks was made by a car-borne team towards the end of the year at Ningyô-tôgé in the Chugoku massif, Southwest Japan. It was confirmed by the geological research that the uranium minerals occur in conglomerates and sandstones of the Neogene Tertiary unconformably overlying the granites.The task of detailed survey for economic development was handed over to the Atomic Fuel Corporation which was established in 1956. The Corporation proceeded to trenching, geophysical and geochemical prospecting, drilling and tunnelling. As the result of these operations, three million tons of the ore reserves containing two thousands tons of uranium metal have been recognized.The uranium ores of Ningyô-tôgé are soft and porous, and the uranium minerals occurring as finegrained crystals in the matrix are easily soluble in acid. Such characteristice of the ore enable 1) to raise their grade several times as high by washing and screening, 2) to exploit by the hydraulic method and 3) to extract the uranium under the mild condition. Furthermore, it must be noted that there are almost no minerals containing elements which interfere with the refining process or possess high cross-section for neutron absorption.

著者

一国 雅巳

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.16, no.75, pp.12-15, 1966-02-28 (Released:2010-03-04)

参考文献数

22

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There are many field evidences suggesting that the limonite deposits of the Akita iron mine were formed by sedimentation of hydrous ferric oxides separated from iron-containing spring waters. The ferruginous precipitates adsorbed various substances from the spring waters, being amorphous when formed. We have, however, no information on the environmental conditions of the precipitation and the mode of crystallization of the precipitates. It is of particular importance from a geochemical point of view to define the temperature and the pH of the solution from which the precipitates formed, and to elucidate the processes of crystallization after the sedimentation of the precipitates.The mineralogical and chemical features of the limonite ores are much suggestive of the genesis of the deposits. The ores, composed mainly of goethite and jarosite, have low crystallinity, which may provide an evidence that they were formed at ordinary temperatures. The chemical compositions of the ores are shown in Table 1. Considering the results of investigations on aging of hydrous ferric oxides and on coprecipitation of anions with insoluble hydrous oxides, the present author concludes that the precipitation and crystallization of hydrous ferric oxides took place at ordinary temperatures and at low pH, presumably at pH 2 to 3.In consequence, we may summarize the formation of the limonite deposits as follows : acidic spring waters, containing ferrous iron, phosphates and sulfates, precipitated hydrous ferric oxides during their flow on the ground surface. A certain microbiological process accelerated the oxidation of ferrous iron. The accumulation and the subsequent crystallization of the precipitates containing phosphates and sulfates have formed finally the limonite deposits composed of goethite, jarosite and some iron phosphate minerals.

著者

奥野 孝晴

出版者

The Society of Resource Geology

雑誌

鉱山地質 (ISSN:00265209)

巻号頁・発行日

vol.20, no.100, pp.125-131, 1970-05-10 (Released:2009-06-12)

参考文献数

2

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Since the first discovery of uranium mineralization in the Mesozoic lacustrine. Kwanmon group in 1966, many indications of the uranium deposits had been found in the province of West Chugoku and North Kyushu. This paper mainly presents of the deposits in the Toyota district, Yamaguchi Prefecture, as a typical example of them. The deposits are classified into four types by their modes of occurrence, namely, the dike-type, the fault fracture-type, the sandstone-type and the carbonaceous material-type. The following has been revealed after the geological investigation. (1) The dike-type and fault fracture-type deposits are distributed in a straight line which runs parallel to the Nagato Tectonic Line of NE-SW trend. (2) Most sandstone-type deposits occur within a restricted stratigraphical horizon. (3) The grade of radioactive disequilibrium is closely related with the modes occurrence of the ore. (4) Thuringite in dikes and sandstones plays an important role of concentrating of uranium. (5) Uraninite, pitchblende, autunite, torbernite, uranophane, beta-uranophane and phosphouranylite are identified-in the enriched zones of the deposits.