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Geosciences LibreTexts

5.4: Unicoi 2 Greenstone

  • Page ID
    11150
  • Outcrop and Hand Sample Photos and Videos

    Click on the image to enlarge.

    The greenstone (metamorphosed basalt; greenish) is on the right. The sandstone unit is on the left. There is near vertical primary bedding here. Can you see how the metamorphic foliation of the greenstone is at an angle to the bedding plane of the sandstone?

    Can you see the amygdules and vesicles in the greenstone? These are filled with chlorite and zeolites.

    Thumbnail for the embedded element "Unicoi 2 Greenstone 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=381

    Thin Section Photos and Videos

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

    The center of this thin section image is a partially filled vesicle (amigdule). The white in ppl is a hole in the amygdule The chlorite (green) shows anomalous interference colors – this is “Berlin blue.” In xpl, you can see the remnants of plagioclase microphenocrysts in the surrounding metabasalt.

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

    The amygdules are clearly visible in this image. Some are clearly stretched by metamorphism.