| Reference Type | Journal (article/letter/editorial) |
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| Title | Chemical variation in micas from the Cairngorm pluton, Scotland |
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| Journal | Mineralogical Magazine | ISSN | 0026-461X |
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| Authors | Harrison, T. N. | Author |
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| Year | 1990 (September) | Volume | 54 |
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| Issue | 376 |
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| Publisher | Mineralogical Society |
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| Download URL | https://rruff.info/doclib/MinMag/Volume_54/54-376-355.pdf+ |
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| DOI | doi:10.1180/minmag.1990.054.376.01Search in ResearchGate |
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| Generate Citation Formats |
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| Mindat Ref. ID | 1630 | Long-form Identifier | mindat:1:5:1630:2 |
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| GUID | 0 |
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| Full Reference | Harrison, T. N. (1990) Chemical variation in micas from the Cairngorm pluton, Scotland. Mineralogical Magazine, 54 (376) 355-366 doi:10.1180/minmag.1990.054.376.01 |
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| Plain Text | Harrison, T. N. (1990) Chemical variation in micas from the Cairngorm pluton, Scotland. Mineralogical Magazine, 54 (376) 355-366 doi:10.1180/minmag.1990.054.376.01 |
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| In | (1990, September) Mineralogical Magazine Vol. 54 (376) Mineralogical Society |
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| Abstract/Notes | AbstractElectron microprobe analyses of micas from the Cairngorm pluton in the Eastern Grampian Highlands of Scotland show extensive compositional variation in biotite, despite a lack of chemical variation in the host granite. Biotite has high Fe/(Fe + Mg) (0.6–0.85) and Alvi (0.6–2.1 a.f.u.), and enrichment trends in these two parameters are attributable to the Al-Tschermak and dioctahedral-trioctahedral substitutions, the latter becoming dominant with increasing Alvi content. Ti content is low (0.2–0.4 a.f.u.), and is largely controlled by a Tschermak-type substitution. Biotite is also unusually rich in Mn (up to 2.57 wt. % MnO), which increases with both Alvi and Fe/(Fe+Mg). F contents generally range between 0.55 and 2.05 wt.% All compositional variation in biotite can be attributed to the extensive development of a fluid phase during the late-magmatic and subsolidus evolution of the pluton. The presence of an abundant fluid phase has resulted in the alteration of biotite to muscovite, which has occurred in response to de-stabilization of the biotite as octahedral R2+ cations are lost in favour of Al. Extreme build-up of this fluid phase has resulted in the crystallization of muscovite as a late, interstitial primary phase. Both primary and replacive muscovite have Fe/(Fe+Mg) > 0.50, 15–36 mol. % celadonite and <1 mol. %paragonite. |
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