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GNEISS #2
Garnet Gneiss    -   Other specific examples: #1 | #2 | #3 | #4
Detail of this specimen
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Composition
NORMAL
Quartz
Feldspar
Amphibole
Biotite
ACCESSORY
In red if present

Garnet
Staurolite
Kyanite
Sillimanite
Description
     Banded foliation where the light- colored quartz and feldspar have segregated into layers from the pods/zones of dark colored amphibole and biotite. The mineral bands in this specimen are just beginning to develop, but are distinctly separate from each other putting it in the gneissic category.
Tectonic Association
     Gneisses are typically associated with major mountain building events when shales or clay rich sandstones (wackes), or felsic igneous rocks (e.g. granite, granodiorite, etc.) are metamorphosed through depth of burial, and proximity to batholiths (click picture for larger version).
Type of Metamorphism
  

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