Gneiss containing large eye-shaped augen feldspar porphyroclasts in a foliated matrix of finer minerals. Texture: Gneissose with augen. Rock type: Metamorphic High-grade. Grain size: Coarse augen in fine matrix. Parent rock: Granite/Granodiorite. Minerals present: Feldspar augen, Quartz, Biotite, Muscovite. Formation: Forms from high-grade metamorphism and deformation of coarse-grained granitic rocks, creating eye-shaped feldspar relicts. Common geological settings: Found in deformed granitic terranes; Alps, Appalachians, Himalayas. Common look-alikes and related entries: Gneiss, Granite, Mylonite.
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Last updated
2026-03-30T14:39:30.853813+00:00
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Rocks — U.S. National Park Service. Authoritative overview of rock groups, the rock cycle, and geologic processes.
Gneiss containing large eye-shaped augen feldspar porphyroclasts in a foliated matrix of finer minerals.
How can you identify Augen Gneiss?
Compare several properties rather than relying on colour alone. This entry records rock type: Metamorphic High-grade; texture: Gneissose with augen; grain size: Coarse augen in fine matrix; common minerals: Feldspar augen, Quartz, Biotite, Muscovite. Confirm an important identification with additional field tests or qualified laboratory work.
How does Augen Gneiss form?
Forms from high-grade metamorphism and deformation of coarse-grained granitic rocks, creating eye-shaped feldspar relicts.
Where is Augen Gneiss commonly found?
Found in deformed granitic terranes; Alps, Appalachians, Himalayas.
What is Augen Gneiss commonly confused with?
Augen Gneiss may be confused with Gneiss, Granite, Mylonite. Compare multiple diagnostic properties because colour and surface appearance can overlap.
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