metamorphic

Amphibolite

Amphibolite, chiefly hornblende and plagioclase feldspar

AI-generated identification · may be incorrect

Coarse, mottled dark-green to black and pale gray-white; visible interlocking crystals with a granular texture. Typical hardness is about 5–6 on Mohs; lustre is mostly dull to vitreous, with no consistent cleavage at the hand-specimen scale.

Identified October 4, 2026More metamorphic →

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Physical properties

Formation & geological history

Forms when basaltic or gabbroic rocks undergo medium- to high-grade regional metamorphism; commonly Precambrian, though it occurs across many geological ages.

Uses & applications

Used as crushed stone and aggregate, dimension stone, and occasionally as a decorative material or collectible specimen.

Geological facts

Its dark amphibole minerals and light feldspar give it a characteristic speckled appearance; composition varies between specimens.

Field identification & locations

Common in metamorphic belts and exposed ancient continental crust. This specimen’s coarse green-and-white mineral mixture is consistent with amphibolite, but identification from a photo is not definitive; confirm by checking for abundant amphibole and feldspar.