Green amphibole, typically representing members of the hornblende series, is characterized by its distinct prismatic crystal habit and perfect cleavage at near-60 and 120-degree angles. It is a widespread constituent of metamorphic rocks, often forming elongated, dark green blades that are easily recognizable in hand specimens.
Is this green 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 green amphibole with a known reference. Green 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. Green Amphibole leaves a white to pale green streak.
- 3Read the lusterHold the specimen under a strong light. Green Amphibole typically shows a vitreous to pearly luster.
- 4Match the color rangeCompare against the expected color range: green, dark green, blackish green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, acicular, fibrous, massive.
Often confused with
Green Amphibole vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Green Amphibole leaves white to pale green, Pyroxene leaves white to grey; luster reads vitreous to pearly on Green 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 — Green Amphibole leaves white to pale green, Tourmaline leaves white; luster reads vitreous to pearly on Green Amphibole and vitreous on Tourmaline.
How to tell apart: Streak differs — Green Amphibole leaves white to pale green, Epidote leaves white; luster reads vitreous to pearly on Green Amphibole and vitreous on Epidote.
Often found alongside green amphibole
Minerals reported to co-occur with green amphibole. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₂(Mg,Fe²⁺)₅Si₈O₂₂(OH)₂
- Mohs hardness
- 5-6
- Density
- 3.0-3.5 g/cm³
- Streak
- White to Pale Green
- Luster
- Vitreous to Pearly
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals, Acicular, Fibrous, Massive
- Cleavage
- Perfect in Two Directions At 56 and 124 Degrees
- Rarity
- Common
- Uses
- Collector, Geological Study
- Host rock
- Metamorphic Rocks Like Amphibolites and Schists, Also in Igneous Rocks
- Typical price
- $5-50 thumbnail
Where rockhounds find green amphibole
1 mapped spotsClassic worldwide localities
- Ontario, Canada
- New York, USA
- Valais, Switzerland
- Norway
- Russia
Field-hunting tip
Look in metamorphic rocks like amphibolites and schists, also in igneous rocks country — that is the host setting where green amphibole typically forms. If you start seeing calcite, quartz, biotite in float, you are in the right ground. Field specimens usually show a prismatic crystals, acicular, fibrous, massive habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in West Virginia — start trip planning there.
Common questions
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Find green amphibole on the map
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