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4 hits

  • Thumbnail for ERB-06a
    ERB-06a

    This thin section contains two distinct populations. The background 'matrix' consists of seriate-interlobate feldspar and quartz, with both phases exhibiting microstructures indicative of strain. A decussate fabric of biotite, chlorite, kyanite, and opaques are distributed in pods throughout the quartz and feldspar 'matrix'. Close examination of these pods reveals poikiloblastic host mineral, presumably k-feldspar, which is almost entirely obscured by inclusions. Zircons with radiation halos are extensive within this poikilobastic phase.

  • Thumbnail for A-6-7
    A-6-7

    A continuous foliation for this sample is defined by aligned hornblende, micas, elongate quartz grains and granular aggregates of epidote and clinozoisite. Quartz is either equant or elongate with a granular texture. The hornblende phase is generally subhedral in shape, as are biotite crystals, which appear to be pseudomorphing an earlier mineral phase as evidenced by abundant inclusions. Radiation halos can be found in this sample though their occurrance is rare.

  • Thumbnail for 498
    498

    This sample is quite coarse-grained. Tartan twinning in the k-feldspar is overprinted by flame and blebby lamellae and both are riddled with inclusions of hornblende, micas, and monazite or zircon. Radiation halos are found around the zircons or monazite crystals found as inclusions in biotite grains.

  • Thumbnail for A-6-8B
    A-6-8B

    This sample is an almost monomineralic hornblende amphibolite with trace occurances of poikiloblastic orthoclase and biotite. Biotite growth concentrates along the margins of a high relief, clear mineral with fifth-order birefringence, extreme enough that the inclusions appear to not go extinct. Rarely are radiaiton halos observed in hornblende crystals.