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Geosciences LibreTexts

5.7: A1 B2 Schist

  • Page ID
    11140
  • Outcrop and Hand Sample Photos and Videos

    Click on the image to enlarge.

    This outcrop is on a busy road. The schist is coated in a dark later of pollution from car exhaust, making it look black on the outcrop. A fresh surface reveals a shiny silver schist.

    The staurolite is the large orange porphyroblasts in the hand sample. Dark minerals are biotite. Much of the rock is muscovite, some quartz, a little plagioclase. Kyanite is rumored to be present. Tiny garnets are hardly visible in hand sample.

    Thumbnail for the embedded element "A1 B2 Schist hand sample"

    A YouTube element has been excluded from this version of the text. You can view it online here: pb.libretexts.org/petrology/?p=301

    Thin Section Photos and Videos

    Click on the image to make it larger. 1st = plane polarized light; 2nd = cross-polarized light.

    Area 1

    Biotite (brown in ppl) and staurolite (yellow in ppl, top left) porphyroblasts. High-relief euhedral mineral is garnet. Qtz and muscovite are also present.

    Area 2

    Staurolite (yellow), qtz, garnet (isotropic, high relief), a little muscovite.

    Area 3

    Close up of garnets (+ stl, qtz, musc). Note the pattern of inclusions in the garnet in ppl.

    Area 4

    Entire thin section scan. 1st = ppl; 2nd = xpl. Click on the image to make it larger.

    This thin section is super interesting for thinking about deformation and metamorphic events.

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