Amphibolite
“Dark, tough, and ancient”
Metamorphic
Amphibolite is a dark, dense metamorphic rock dominated by amphibole minerals (usually hornblende) and plagioclase feldspar. It forms from the medium- to high-grade metamorphism of mafic igneous rocks like basalt and gabbro.
Composition
hornblende, plagioclase feldspar, garnet, biotite, epidote
Where Found
Appalachian Mountains (USA), Scandinavia, Scottish Highlands, South India
Mohs Hardness
5-7
Fun Fact
Neolithic people in Europe preferentially sought out amphibolite to make polished stone axes because it is extremely tough and takes a sharp edge.
Test Your Knowledge
What does the presence of amphibolite in a region indicate about its geological past?
Related Specimens
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