Amphibole is a major group of complex inosilicate minerals widely found in metamorphic and igneous rocks. They are most easily identified by their distinct, splintery prismatic crystal habit and cleavage angles of approximately 56 and 124 degrees, which help distinguish them from the similar-looking Pyroxene group.
Is this amphibole?
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 amphibole with a known reference. Amphibole 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. Amphibole leaves a white to gray streak.
- 3Read the lusterHold the specimen under a strong light. Amphibole typically shows a vitreous to silky luster.
- 4Match the color rangeCompare against the expected color range: black, dark green, brown, dark blue, white.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, fibrous, columnar, or massive.
Often confused with
Amphibole vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Amphibole leaves white to gray, Pyroxene leaves white to grey; luster reads vitreous to silky on Amphibole and vitreous to dull on Pyroxene.
How to tell apart: Tourmaline is the harder of the two (Mohs 7-7.5 vs. 5-6); streak differs — Amphibole leaves white to gray, Tourmaline leaves white; luster reads vitreous to silky on Amphibole and vitreous on Tourmaline.
How to tell apart: Streak differs — Amphibole leaves white to gray, Epidote leaves white; luster reads vitreous to silky on Amphibole and vitreous on Epidote.
Often found alongside amphibole
Minerals reported to co-occur with amphibole. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- AB₂C₅Si₈O₂₂(OH,F,Cl)₂
- Mohs hardness
- 5-6
- Density
- 2.8-3.6 g/cm³
- Streak
- White to Gray
- Luster
- Vitreous to Silky
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals, Fibrous, Columnar, Or Massive
- Cleavage
- Perfect in Two Directions At 56 and 124 Degrees
- Rarity
- Common
- Uses
- Industrial, Collector, Decorative
- Host rock
- Igneous and Metamorphic Rocks
- Typical price
- $5-50 for small cabinet specimens
Where rockhounds find amphibole
4 mapped spotsClassic worldwide localities
- Canada
- USA
- Norway
- Italy
- Madagascar
Field-hunting tip
Look in igneous and metamorphic rocks country — that is the host setting where amphibole typically forms. If you start seeing quartz, feldspar, mica in float, you are in the right ground. Field specimens usually show a prismatic crystals, fibrous, columnar, or massive habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Colorado, New Jersey, New York — start trip planning there.
Common questions
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Find amphibole on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
