metamorphic

Amphibolite / Hornblende Schist

Amphibolite

AI-generated identification · may be incorrect

Hardness: 5-6 on the Mohs scale. Color: Dark green to black with white, cream, or brown mineral streaks (plagioclase feldspar and iron staining). Luster: Sub-vitreous to silky/pearly. Texture: Foliated to nematoblastic (lineated amphibole crystals). Cleavage: Distinct prismatic cleavage in amphibole grains.

Hardness: 5-6 on the Mohs scale
Luster: Sub-vitreous to silky/pearly

Identified July 26, 2026More metamorphic →

Explore Amphibolite / Hornblende Schist in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed through regional metamorphism of mafic igneous rocks (such as basalt or gabbro) or clay-rich marls under high temperature and moderate-to-high pressure conditions.

Uses & applications

Used as crushed stone for road construction, railroad ballast, and occasionally as decorative dimension stone in architecture. Also collected as educational rock specimens.

Geological facts

Amphibolites make up a significant portion of ancient continental crust and metamorphic terranes, often revealing the tectonic history of mountain-building events (orogenies).

Field identification & locations

Identified in the field by its dark color, lineated or foliated alignment of dark needle-like amphibole (hornblende) crystals, and alternating light feldspar streaks. Commonly found in metamorphic mountain belts like the Appalachians and Alps. Value: $2-$10 for hand-sized field specimens.