A high-grade metamorphic rock with distinctive banding of light and dark minerals. Represents rocks that have been subjected to extreme heat and pressure deep in the crust. Texture: Gneissic banding. Rock type: Metamorphic Foliated. Grain size: Coarse. Minerals present: Quartz, Feldspar, Mica, Hornblende. Formation: Forms from high-grade regional metamorphism of various parent rocks granite, shale, sandstone . Minerals segregate into alternating light and dark bands. Common geological settings: Found in the cores of mountain ranges and ancient continental shields. Forms at depths of 10-30 km in the crust. Common look-alikes and related entries: Granite, Schist, Migmatite.
Banded rocks — Place this specimen in a broader field-identification workflow.
Foliated rocks — Place this specimen in a broader field-identification workflow.
Gneiss vs Granite — Compare observable properties and safer field tests.
Schist vs Gneiss — Compare observable properties and safer field tests.
Sources, scope & corrections
These authoritative resources support category-level nomenclature, terminology, identification methods, and safety. When a specimen-specific safety warning appears, the public-health source listed here directly supports that precaution. They are not line-by-line citations for every other property on this entry, and natural specimens vary.
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GeoMiner
Last updated
2026-03-30T14:39:42.618569+00:00
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Published; not independently peer-reviewed
Rocks — U.S. National Park Service. Authoritative overview of rock groups, the rock cycle, and geologic processes.
A high-grade metamorphic rock with distinctive banding of light and dark minerals. Represents rocks that have been subjected to extreme heat and pressure deep in the crust.
How can you identify Gneiss?
Compare several properties rather than relying on colour alone. This entry records rock type: Metamorphic Foliated; texture: Gneissic banding; grain size: Coarse; common minerals: Quartz, Feldspar, Mica, Hornblende. Confirm an important identification with additional field tests or qualified laboratory work.
How does Gneiss form?
Forms from high-grade regional metamorphism of various parent rocks granite, shale, sandstone . Minerals segregate into alternating light and dark bands.
Where is Gneiss commonly found?
Found in the cores of mountain ranges and ancient continental shields. Forms at depths of 10-30 km in the crust.
What is Gneiss commonly confused with?
Gneiss may be confused with Granite, Schist, Migmatite. Compare multiple diagnostic properties because colour and surface appearance can overlap.
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