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4 hits

  • Thumbnail for 484
    484

    Perthitic intergrowths of k-feldspar and albite are prevalent throughout this coarse-grained, nearly allotriomorphic granite. Riebeckite and biotite are found intergrown together in anhedral masses. The rare tiny, equant olivine crystal is observable.

  • Thumbnail for 483
    483

    The k-feldspars in this granite have prominent perthitic intergrowths, which overprint obvious tartan and Carlsbad twins. Feldspars growth is more euhedral than that of quartz or biotite. A single, tiny, fractured olivine crystal is present along the margin of the thin section.

  • Thumbnail for 515
    515

    This hypidiomorphic inequigranular granite has rather scalloped grain boundaries, particularly among the quartzofeldspathic phases, though the biotite grains exhibit similar textures with the feldspars. One anhedral biotite grain has bulbs protruding into the neighboring k-feldspar grain. Quartz extinction is uniform. Olivine is present in trace amounts and the highly-fractured phase is typically surrounded by a thick rim of iddingsite.

  • Thumbnail for 485
    485

    The k-feldspars in this granite have prominent perthitic intergrowths, which overprint obvious tartan and Carlsbad twins. Feldspars growth is more euhedral than that of other phases, though grain boundaries between feldspars are rather sutured. Anhedral riebeckite and biotite have seive-like textures. Olivine, if present, is found in trace amounts.