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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 990
    990

    The minerals in this sample all appear to intergrow with one another. Most grain boundaries are lobate, especially between feldspar phases and flame lamellae and perthitic intergrowths abound. Although a few hornblende crystals are euhdral in shape, the majority are found as rims around possible clinopyroxene or olivine grains and they tend to group with the other mafic phases. Euhedral apatite appear throughout.

  • 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.

  • 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.