Blue amphibole refers to members of the glaucophane-riebeckite series, typically found in blueschist metamorphic terrains. It is easily identified by its distinctive blue color and often fibrous or needle-like habit. Collectors must exercise extreme caution due to its potential asbestiform nature.
Is this blue 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 blue amphibole with a known reference. Blue 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. Blue Amphibole leaves a white to light blue streak.
- 3Read the lusterHold the specimen under a strong light. Blue Amphibole typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: blue, blue-gray, lavender-blue.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: fibrous, acicular, or prismatic crystals.
Often confused with
Blue Amphibole vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Tourmaline is the harder of the two (Mohs 7-7.5 vs. 5-6); streak differs, so Blue Amphibole leaves white to light blue, Tourmaline leaves white.
How to tell apart: Streak differs, so Blue Amphibole leaves white to light blue, Actinolite leaves white; luster reads vitreous on Blue Amphibole and vitreous to silky on Actinolite.
How to tell apart: Dumortierite is the harder of the two (Mohs 7-8.5 vs. 5-6); streak differs, so Blue Amphibole leaves white to light blue, Dumortierite leaves white.
Often found alongside blue amphibole
Minerals reported to co-occur with blue amphibole. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₂(Fe²⁺₃Fe³⁺₂)Si₈O₂₂(OH)₂
- Mohs hardness
- 5-6
- Density
- 3.0-3.4 g/cm³
- Streak
- White to Light Blue
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Fibrous, Acicular, Or Prismatic Crystals
- Cleavage
- Perfect in 2 Directions
- Rarity
- Common
- Uses
- Collector
- Host rock
- Metamorphic Schists and Blueschist Facies
- Typical price
- $10-50 per specimen depending on fiber density
Where rockhounds find blue amphibole
1 mapped spotsClassic worldwide localities
- Western Australia
- South Africa
- California, USA
- Japan
- Switzerland
Field-hunting tip
Look in metamorphic schists and blueschist facies country, the host setting where blue amphibole typically forms. If you start seeing quartz, epidote, chlorite in float, you are in the right ground. Field specimens usually show a fibrous, acicular, or prismatic crystals 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 blue amphibole on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
