4 0 0 0 OA リチウムに富む含水準輝石族新鉱物「村上石」の結晶化学
- 著者
- 今岡 照喜 永嶌 真理子
- 出版者
- 公益社団法人 東京地学協会
- 雑誌
- 地学雑誌 (ISSN:0022135X)
- 巻号頁・発行日
- vol.131, no.2, pp.235-256, 2022-04-25 (Released:2022-05-13)
- 参考文献数
- 98
- 被引用文献数
- 3
The mineralogical characteristics of metasomatic Li-minerals in Iwagi Islet, sugilite, katayamalite, murakamiite, Li-rich pectolite, zektzerite, sogdianite and taeniolite are summarized. These Li-minerals occur in metasomatic albitite, which contains 500 ppm Li. Such a high-Li albitite content is unusual amongst metasomatic rocks in Setouchi Province of SW Japan. Albitite forms small bodies that are several tens of centimeters to tens of meters in size, and are disseminated in a host granite of Late Cretaceous age. It shows conspicuous strain-induced textures. Murakamiite and Li-rich pectolite form a solid solution with Li × 100/(Li + Na) atomic ratios ranging from 44.2 to 60.1, and Na line profiles show a zoning structure in which Na decreases from core to rim. Albitite-normalized element concentrations vary systematically with the ionic radius of the element; normalized concentrations of cations with the same valence roughly form a simple convex parabolic curve when plotted against the ionic radius. This indicates that the element partitioning of murakamiite and pectolite during metasomatism to form albitite took place under the strong control of a crystal structure, quasi-equilibrated with metasomatic fluids and coexisting minerals. The δ7Li values of murakamiite and Li-rich pectolite show a wide range from −9.1 to +0.4‰ (average −2.9‰), and no obvious correlation with Li content is observed. These δ7Li values should have resulted from hydrothermal fluid–rock interactions at temperatures of 300-600°C (hydrothermal stages). The very low δ7Li values down to −9.1‰ may have originated from intra-crystalline Li isotope diffusion, or involvement of deep-seated, Li–Na-enriched subduction-zone fluids with low δ7Li values. The occurrence of porous zircon, dalyite, and mantles of zektzerite and/or sogdianite on resorbed zircon in albitite suggests that those zirconium silicate minerals are the products of metasomatic mineral replacement reactions by dissolution–reprecipitation processes associated with Na-, K-, and Li-rich hydrothermal fluids.
2 0 0 0 OA 緑簾石族鉱物の結晶化学:解析と合成による新たな展開
- 著者
- 永嶌 真理子
- 出版者
- 日本結晶学会
- 雑誌
- 日本結晶学会誌 (ISSN:03694585)
- 巻号頁・発行日
- vol.54, no.5, pp.255-262, 2012-10-31 (Released:2012-11-06)
- 参考文献数
- 40
Epidote-group minerals are important rock-forming minerals and play a role as a reservoir of transition metal elements, strontium, rare-earth elements and water. They are formed under a variety of geological conditions. Both natural epidotes with complex chemical compositions and synthetic ones with idealized compositions have been investigated to understand their chemico-crystallographical features. In this paper, recent studies on synthetic and natural monoclinic epidotes are reviewed in terms of distributions of cations in coordination polyhedra and structural variations due to cation substitutions. New circumstances such as ‘ghost’ difference Fourier peak as an index of low-crystallinity epidotes and OH-free structure (oxyallanite) are introduced, and subjects for the future studies are proposed.
2 0 0 0 OA 岩城島産エジリンアルビタイト中のデーリー石とゼッツェル石
- 著者
- 今岡 照喜 秋田 幸穂 永嶌 真理子
- 出版者
- 公益社団法人 東京地学協会
- 雑誌
- 地学雑誌 (ISSN:0022135X)
- 巻号頁・発行日
- vol.130, no.3, pp.369-378, 2021-06-25 (Released:2021-07-20)
- 参考文献数
- 34
- 被引用文献数
- 3
愛媛県岩城島の白亜紀エジリンアルビタイトより稀なK–Zr珪酸塩鉱物であるデーリー石とLi–Na–Zr珪酸塩鉱物であるゼッツェル石が見いだされた。デーリー石とゼッツェル石のEPMA分析結果からそれぞれ(K1.93Ba0.01)Σ1.94(Zr0.99Hf0.02)Σ1.01Si5.98O15およびNa1.03(Zr0.96Hf0.02Y0.01Sc0.01)Σ1.00Li1.02(Si5.95Al0.04)Σ5.99O15の実験式が得られる。多孔質ジルコン,デーリー石,および不安定なジルコンを被覆するゼッツェル石の産状から,このアルビタイトは熱水活動時期におけるNa,K,Liに富んだ流体によるジルコニウム鉱物の分解と沈殿による交代反応の記録をよく保存している。これは日本列島におけるデーリー石とゼッツェル石産出の最初の報告である。
- 著者
- 伊藤 修一 永嶌 真理子
- 雑誌
- 一般社団法人日本鉱物科学会2021年年会・総会
- 巻号頁・発行日
- 2021-08-11