Eckermannite is a relatively rare sodium-rich amphibole found in alkaline igneous environments. Collectors look for its characteristic blue to blue-green elongated prismatic crystals, which often form in complex assemblages with other alkaline minerals.
Is this eckermannite?
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 eckermannite with a known reference. Eckermannite 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. Streak: greenish white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: blue green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, acicular, fibrous.
Often confused with
Eckermannite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Eckermannite leaves greenish white, Glaucophane leaves blue-gray.
How to tell apart: Streak differs, so Eckermannite leaves greenish white, Arfvedsonite leaves deep bluish gray, gray-green.
Often found alongside eckermannite
Minerals reported to co-occur with eckermannite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaNa₂(Mg₄Al)Si₈O₂₂(OH)₂
- Mohs hardness
- 5-6
- Density
- 3-3.17 g/cm³
- Colors
- Streak
- Greenish white
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic crystals, acicular, fibrous
- Cleavage
- Perfect on {110}, intersecting at 56° and 124°; [parting on {010}]
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In a jadeitite-amphibole fels rock, likely formed under blueschist facies conditions
Where rockhounds find eckermannite
Classic worldwide localities
- Jade Mine Tract, Kachin Province, Myanmar
Field-hunting tip
Where it forms: In a jadeitite-amphibole fels rock, likely formed under blueschist facies conditions. If you start seeing jadeite, albite in float, you are in the right ground. Typical habit: prismatic crystals, acicular, fibrous. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify eckermannite?+
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What rocks look like eckermannite?+
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Find eckermannite on the map
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