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    The relation between chemical composition and paragenesis in the biotite micas of igneous rocks
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    Abstract:
    Biotite micas from igneous rocks differ from one another mainly in their contents of SiO 2 , Al 2 O 3 , MgO, total Fe as FeO and, to a less extent, in TiO 2 . The variation in amount of each of these oxides was investigated. It was found that some depend on the nature of minerals associated with the biotite, others on the general nature of the rock containing the biotite.
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    Paragenesis
    The paragenesis of ludwigite has been frequently described by Geijer, Watanabe, Tilley and others, however, that of paigeite has not been described in detail. The present paper purports to describe the paragenesis of paigeite from the Kamaishi mine, Iwate Pref., Japan, and to clarify the difference in the paragenesis of paigeite and ludwigite, moreover, to discuss their genesis. Assuming a similarity of temperature and pressure during the formation of paragenesis of paigeite and ludwigite, and that chemical potentials of H2O, CO2, Na2O, K2O, B2O3 in the pore fluids participating in the formation of these parageneses were alike, and further that changes in the chemical potential of Fe had no effect on the composition of diopside, forsterite, phlogopite, spinel and tourmaline, but that, they it may be had a striking effect on the composition of the mineral of ludwigite series, concluded that the paragenesis of paigeite was formed in a condition where the chemical potential of O2 in the pore fluids was low and that of Fe in the system was high, whereas, the paragenesis of ludwigite was formed in a condition where the chemical potential of O2 was high and that of Fe was low.
    Paragenesis
    Citations (2)
    Biotite micas from igneous rocks differ from one another mainly in their contents of SiO 2 , Al 2 O 3 , MgO, total Fe as FeO and, to a less extent, in TiO 2 . The variation in amount of each of these oxides was investigated. It was found that some depend on the nature of minerals associated with the biotite, others on the general nature of the rock containing the biotite.
    Paragenesis
    Citations (137)
    Fissure-filling and vein deposits in the region of the Lexington dome have a paragenesis that is constant throughout the district. Regional zoning shows a concentric pattern, with fluorite and dark sphalerite in the central region grading to barite, galena, and light-colored sphalerite in the outer zone. The deposits are spatially related to faults and fractures cutting the Lexington dome, and are attributed to low-temperature solutions from a deep-seated magmatic source.
    Paragenesis
    Mineral resource classification
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