反蛇纹石

反蛇纹石
	蛇纹岩中的反蛇纹石結晶，標本地點波蘭
基本資料
類別	页硅酸盐矿物
化学式	(Mg, Fe)3Si2O5OH4
性質
晶系	單斜晶系

反蛇纹石（英語：Antigorite）是層狀蛇紋石亞群之一種，屬页硅酸盐矿物^[1]，其理想化學式為(Mg,Fe²⁺)₃Si₂O₅(OH)₄^[2]。它是蛇紋石的高壓同质异形体，常見於變質蛇紋岩中。反蛇纹石及其蛇紋石同质异形体在俯衝帶動力學中具有著重要作用，由於其相對脆弱和高含量的水（高達 13 ％）^[3] ^[4]. 它的學名是以意大利/瑞士邊境地區的 Geisspfad 蛇紋岩 Valle Antigorio ^[5] 命名，通常用作珠寶和雕刻中的寶石。

地質產狀

反蛇纹石是低溫、高壓（或高變形）產物，在伸展和擠壓構造體系都有^[6]。蛇紋石在俯衝帶的超基性綠片岩相中分佈很多。出露到地球表面的蛇紋石也常見。含反蛇纹石的蛇紋岩通常具高度變形的紋理，表明它們形成的動態環境。反蛇纹石通常有伴生的磁鐵礦、綠泥石和碳酸鹽礦物^[7]。橄欖石在熱液作用、低度變質作用和風化作用下亦能轉變為反蛇纹石，在這種環境下，它常與滑石和碳酸鹽伴生。

3Mg₃SiO₄ (橄欖石) + H₂O + SiO₂ → 2Mg₃Si₂O₅OH₄ (蛇紋石)
2Mg₃Si₂O₅OH₄ (蛇紋石) + CO₂ → 2Mg₃Si₄O₁₀OH₂ (滑石) + 3MgCO₃ (菱鎂礦)+ H₂O ^[8]

物理性質

反蛇纹石的顏色通常是深綠色，但也可能是淡黃色、灰色、棕色或黑色。它的莫氏硬度為 3.5–4，光澤呈玻璃狀至油膩狀^[9]。蛇紋石的比重為 2.5-2.6。屬單斜晶系並具雲母狀解理，這是页硅酸盐矿物的一個特性，並且難以融合^[10]。由反蛇纹石組成的蛇紋岩通常是糜棱岩。構成這些岩石的葉蛇纹石顆粒非常細（大約 1 到 10 微米）並且是纖維狀的，這種岩石紋理是由于晶格優選取向引起的^[11]。

參考文獻

^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
^ "AMCSD Search Results". rruff.geo.arizona.edu.
^ Dódony, István; Pósfai, Mihály; Buseck, Peter R. (2002). "Revised structure models for antigorite: An HRTEM study". American Mineralogist. 87 (10): 1443–1457. Bibcode:2002AmMin..87.1443D. doi:10.2138/am-2002-1022. ISSN 0003-004X. S2CID 55304426.
^ Ulmer, P.; Trommsdorff, V. (1995). "Serpentine Stability to Mantle Depths and Subduction-Related Magmatism". Science. 268 (5212): 858–861. Bibcode:1995Sci...268..858U. doi:10.1126/science.268.5212.858. ISSN 0036-8075. PMID 17792181. S2CID 12878042.
^ "Antigorite Mineral Data". webmineral.com.
^ Ribeiro Da Costa, Isabel; Barriga, Fernando J. A. S. Viti; Mellini, Marcello; Wicks, Frederick J. (2008). "Antigorite in deformed serpentinites from the Mid-Atlantic Ridge". European Journal of Mineralogy. 20 (4): 563–572. Bibcode:2008EJMin..20..563R. doi:10.1127/0935-1221/2008/0020-1808.
^ Ribeiro Da Costa, Isabel; Barriga, Fernando J. A. S. Viti; Mellini, Marcello; Wicks, Frederick J. (2008). "Antigorite in deformed serpentinites from the Mid-Atlantic Ridge". European Journal of Mineralogy. 20 (4): 563–572. Bibcode:2008EJMin..20..563R. doi:10.1127/0935-1221/2008/0020-1808.
^ Page 5 Deer, Howie, Zussman "An Introduction to the Rock Forming Minerals" ISBN 0 582 44210 9
^ "Antigorite Mineral Data". webmineral.com.
^ "Antigorite gemstone information". www.gemdat.org.
^ Horn, Charis; Bouilhol, Pierre; Skemer, Philip (2020). "Serpentinization, Deformation, and Seismic Anisotropy in the Subduction Mantle Wedge". Geochemistry, Geophysics, Geosystems. 21 (4). Bibcode:2020GGG....2108950H. doi:10.1029/2020GC008950. ISSN 1525-2027.

[”1”-1] Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.

[”2”-2] "AMCSD Search Results". rruff.geo.arizona.edu.

[”3”-3] Dódony, István; Pósfai, Mihály; Buseck, Peter R. (2002). "Revised structure models for antigorite: An HRTEM study". American Mineralogist. 87 (10): 1443–1457. Bibcode:2002AmMin..87.1443D. doi:10.2138/am-2002-1022. ISSN 0003-004X. S2CID 55304426.

[”4”-4] Ulmer, P.; Trommsdorff, V. (1995). "Serpentine Stability to Mantle Depths and Subduction-Related Magmatism". Science. 268 (5212): 858–861. Bibcode:1995Sci...268..858U. doi:10.1126/science.268.5212.858. ISSN 0036-8075. PMID 17792181. S2CID 12878042.

[”5”-5] "Antigorite Mineral Data". webmineral.com.

[”6”-6] Ribeiro Da Costa, Isabel; Barriga, Fernando J. A. S. Viti; Mellini, Marcello; Wicks, Frederick J. (2008). "Antigorite in deformed serpentinites from the Mid-Atlantic Ridge". European Journal of Mineralogy. 20 (4): 563–572. Bibcode:2008EJMin..20..563R. doi:10.1127/0935-1221/2008/0020-1808.

[”7”-7] Ribeiro Da Costa, Isabel; Barriga, Fernando J. A. S. Viti; Mellini, Marcello; Wicks, Frederick J. (2008). "Antigorite in deformed serpentinites from the Mid-Atlantic Ridge". European Journal of Mineralogy. 20 (4): 563–572. Bibcode:2008EJMin..20..563R. doi:10.1127/0935-1221/2008/0020-1808.

[”8”-8] Page 5 Deer, Howie, Zussman "An Introduction to the Rock Forming Minerals" ISBN 0 582 44210 9

[”9”-9] "Antigorite Mineral Data". webmineral.com.

[”10”-10] "Antigorite gemstone information". www.gemdat.org.

[”11”-11] Horn, Charis; Bouilhol, Pierre; Skemer, Philip (2020). "Serpentinization, Deformation, and Seismic Anisotropy in the Subduction Mantle Wedge". Geochemistry, Geophysics, Geosystems. 21 (4). Bibcode:2020GGG....2108950H. doi:10.1029/2020GC008950. ISSN 1525-2027.

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