How can you identify Anorthosite?

Compare several properties rather than relying on colour alone. This entry records rock type: Igneous Intrusive; texture: Phaneritic; grain size: Very coarse; common minerals: Plagioclase 90%, Pyroxene minor, Olivine minor. Confirm an important identification with additional field tests or qualified laboratory work.

What is Anorthosite commonly confused with?

Anorthosite may be confused with Gabbro, Marble, Diorite. Compare multiple diagnostic properties because colour and surface appearance can overlap.

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Anorthosite identification and geology

Intrusive igneous rock composed almost entirely 90% of plagioclase feldspar. Common on the Moon. Texture: Phaneritic. Rock type: Igneous Intrusive. Grain size: Very coarse. Minerals present: Plagioclase 90%, Pyroxene minor, Olivine minor. Formation: Forms from accumulation of plagioclase crystals floating in mafic magma chambers. Major component of lunar highlands. Common geological settings: Adirondacks New York , Labrador, Norway, lunar highlands; found in Proterozoic massifs. Common look-alikes and related entries: Gabbro, Marble, Diorite.

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Gabbro
Marble
Diorite

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.

Editorial owner: GeoMiner
Last updated: 2026-03-30T14:38:09.105519+00:00
Review status: Published; not independently peer-reviewed

Rocks — U.S. National Park Service. Authoritative overview of rock groups, the rock cycle, and geologic processes.
Can you identify my rock or mineral? — U.S. Geological Survey. Identification limitations and routes to in-person professional verification.

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Common questions

What is Anorthosite?: Intrusive igneous rock composed almost entirely 90% of plagioclase feldspar. Common on the Moon.
How can you identify Anorthosite?: Compare several properties rather than relying on colour alone. This entry records rock type: Igneous Intrusive; texture: Phaneritic; grain size: Very coarse; common minerals: Plagioclase 90%, Pyroxene minor, Olivine minor. Confirm an important identification with additional field tests or qualified laboratory work.
How does Anorthosite form?: Forms from accumulation of plagioclase crystals floating in mafic magma chambers. Major component of lunar highlands.
Where is Anorthosite commonly found?: Adirondacks New York , Labrador, Norway, lunar highlands; found in Proterozoic massifs.
What is Anorthosite commonly confused with?: Anorthosite may be confused with Gabbro, Marble, Diorite. Compare multiple diagnostic properties because colour and surface appearance can overlap.

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Anorthosite identification and geology

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Sources, scope & corrections

Common questions