metamorphic
Amphibolite
Amphibolite, typically composed mainly of hornblende (amphibole) and plagioclase feldspar
AI-generated identification · may be incorrectDark gray to black, coarse and crystalline with a speckled appearance; minerals commonly have a shiny or vitreous luster. Hardness is generally about 5–6 on Mohs; exact composition and properties cannot be confirmed from the photo alone.
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Physical properties
Dark gray to black, coarse and crystalline with a speckled appearance; minerals commonly have a shiny or vitreous luster. Hardness is generally about 5–6 on Mohs; exact composition and properties cannot be confirmed from the photo alone.
Formation & geological history
Forms when basaltic or gabbroic rock is metamorphosed under moderate-to-high heat and pressure, commonly during mountain building. Its age depends on the source rock and metamorphic event.
Uses & applications
Used as crushed aggregate and building or decorative stone; attractive, durable pieces may be collected or polished.
Geological facts
Amphibolite is named for its abundant amphibole minerals, especially hornblende, and commonly shows dark elongated crystals among lighter feldspar.
Field identification & locations
The pictured specimen’s dark, coarse, mottled texture is consistent with amphibolite, but a close mineral examination would be needed for a firm identification. It occurs in metamorphic belts worldwide; typical hand specimens have modest value.
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