Amphibolite is a metamorphic rock composed mainly of amphibole minerals like hornblende and plagioclase feldspar. It is characterized by its dark, often foliated or banded appearance and typically forms through the regional metamorphism of mafic igneous rocks.
Is this amphibolite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch amphibolite with a known reference. Amphibolite sits at Mohs 5-6 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Amphibolite leaves a white to gray streak.
- 3Read the lusterHold the specimen under a strong light. Amphibolite typically shows a subvitreous to pearly luster.
- 4Match the color rangeCompare against the expected color range: black, dark green, dark gray.
- 5Look at form & habitTypical habit: foliated.
Often confused with
Amphibolite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Amphibolite leaves white to gray, Hornblende leaves grayish-white; luster reads subvitreous to pearly on Amphibolite and vitreous on Hornblende.
How to tell apart: Streak differs — Amphibolite leaves white to gray, Schist leaves white; luster reads subvitreous to pearly on Amphibolite and pearly on Schist.
How to tell apart: Streak differs — Amphibolite leaves white to gray, Gneiss leaves white; luster reads subvitreous to pearly on Amphibolite and vitreous on Gneiss.
Often found alongside amphibolite
Minerals reported to co-occur with amphibolite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Mohs hardness
- 5-6
- Density
- 2.9-3.2 g/cm³
- Colors
- Streak
- White to Gray
- Luster
- Subvitreous to Pearly
- Transparency
- Opaque
- Crystal habit
- Foliated
- Cleavage
- None
- Rarity
- Common
- Uses
- Decorative, Construction, Architectural
- Host rock
- Regional Metamorphism of Basaltic Rocks
- Typical price
- $5-30 per slab or specimen
Where rockhounds find amphibolite
4 mapped spotsClassic worldwide localities
- Adirondack Mountains, USA
- Scotland
- Scandinavia
- Alps
- Canada
Field-hunting tip
Look in regional metamorphism of basaltic rocks country — that is the host setting where amphibolite typically forms. If you start seeing hornblende, plagioclase, garnet in float, you are in the right ground. Field specimens usually show a foliated habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in North Carolina, Maryland, South Carolina — start trip planning there.
Common questions
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Find amphibolite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
