metamorphic
Amphibolite
Amphibolite, composed chiefly of hornblende-group amphibole and plagioclase feldspar
AI-generated identification · may be incorrectDark green to black, coarse-grained, with glittering amphibole and pale feldspar grains; Mohs hardness about 5–6, vitreous to dull luster, typically nonfoliated or weakly foliated. Exact mineral proportions and properties require testing.
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Physical properties
Dark green to black, coarse-grained, with glittering amphibole and pale feldspar grains; Mohs hardness about 5–6, vitreous to dull luster, typically nonfoliated or weakly foliated. Exact mineral proportions and properties require testing.
Formation & geological history
Forms when mafic igneous rocks such as basalt or gabbro undergo medium- to high-grade metamorphism. It occurs in ancient metamorphic belts across many geological ages.
Uses & applications
Used as crushed stone, aggregate, and occasionally decorative building stone; attractive pieces may be collected or cut for ornamental use.
Geological facts
Amphibolite is a metamorphic rock defined by its amphibole-rich composition, commonly hornblende with plagioclase.
Field identification & locations
The specimen’s dark green, speckled appearance is consistent with amphibolite, but a photo cannot confirm the identification; look for interlocking dark amphibole and lighter feldspar grains. Found in metamorphic terrains worldwide.
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