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5.2: UM1 Soapstone and Serpentinite

  • Page ID
    11148
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    Outcrop and Hand Sample Photos and Videos

    This outcrop is on the appropriately named Soapstone Rd. It is next to a creek and a small house that (at least used to) contain many, many dogs.

    Can you see the very weak foliation of the rock in the 1st picture (best observed in the left side of the photo)?

    UM1-2-scaled-1.jpg

    The “bumpy” texture seems to be due in part to the weathering of the inhomogeneous rock. If you watch the YouTube video of the hand sample, clasts of ultramafic rock (peridotite?) are surrounded by reaction rims of serpentine. The main rock contains talc (feels slippery), magnetite, serpentine, and chlorite.

    UM1-1-Serpentinite-and-soapstone-scaled-1.jpg
    UM1-3-scaled-1.jpg

    Thin Section Photos and Videos

    1st = plane polarized light; 2nd = cross-polarized light.

    Unfortunately, we don’t have a thin section of one of the ultramafic clasts. However, you can see some of the minerals in the main section of the rock here. At the top = lower interference colors and fibrous = serpentine minerals and chlorite. At the bottom, higher-order interference colors = talc. Magnetite is opaque.

    UM1-ppl-4x-300x225.jpg
    UM1-xpl-4x-300x225.jpg

    Entire thin section scan. 1st = ppl; 2nd = xpl. 

    UM1-ppl-scaled-1.jpg
    UM1-xpl-scaled-1.jpg

    This page titled 5.2: UM1 Soapstone and Serpentinite is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Elizabeth Johnson and Juhong Christie Liu (Virtual Library of Virginia) via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.