Ferro-edenite is a member of the calcic amphibole group, typically occurring as dark, prismatic crystals in skarns or metamorphosed carbonate rocks. It is visually indistinguishable from many other dark amphiboles without chemical analysis, though its occurrence in alkaline-rich metamorphic environments is a useful diagnostic hint for collectors.
Is this ferro-edenite?
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 ferro-edenite with a known reference. Ferro-edenite 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: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, elongated grains.
Often confused with
Ferro-edenite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside ferro-edenite
Minerals reported to co-occur with ferro-edenite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaCa₂Fe₅Si₇AlO₂₂(OH)₂
- Mohs hardness
- 5-6
- Density
- 3-3.1 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Semitransparent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic crystals, elongated grains
- Cleavage
- Good on {110}, intersecting at ~56° and ~124°; partings on {100}, {001}
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- An early or deuteric phase replacing pyroxene in syenitic ring complexes; from medium-grade metamorphic amphibolites and gneisses; from plutonic igneous rocks
Where rockhounds find ferro-edenite
Classic worldwide localities
- Tibchi ring complex, Nigeria
Field-hunting tip
Where it forms: An early or deuteric phase replacing pyroxene in syenitic ring complexes; from medium-grade metamorphic amphibolites and gneisses; from plutonic igneous rocks. If you start seeing pyroxene, ferro-actinolite, monazite in float, you are in the right ground. Typical habit: prismatic crystals, elongated grains. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ferro-edenite?+
Where is ferro-edenite found?+
What rocks look like ferro-edenite?+
What minerals are found with ferro-edenite?+
What kind of rock does ferro-edenite form in?+
What is ferro-edenite used for?+
Find ferro-edenite on the map
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