Ferro-ferri-nybøite is a rare member of the amphibole supergroup typically found in alkaline igneous complexes. Collectors usually identify it as dark, prismatic crystals embedded within nepheline syenites or associated pegmatites. It is highly valued for its mineralogical rarity and specific chemical composition.
Is this ferro-ferri-nybøite?
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-ferri-nybøite with a known reference. Ferro-ferri-nybøite 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. Ferro-ferri-nybøite leaves a pale grey streak.
- 3Read the lusterHold the specimen under a strong light. Ferro-ferri-nybøite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: dark blue, dark green, black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals.
Often confused with
Ferro-ferri-nybøite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Ferro-ferri-nybøite leaves pale grey, Arfvedsonite leaves grey to bluish-grey.
How to tell apart: Streak differs — Ferro-ferri-nybøite leaves pale grey, Riebeckite leaves blue-gray.
How to tell apart: Streak differs — Ferro-ferri-nybøite leaves pale grey, Magnesio-riebeckite leaves blue-gray; luster reads vitreous on Ferro-ferri-nybøite and silky on Magnesio-riebeckite.
Often found alongside ferro-ferri-nybøite
Minerals reported to co-occur with ferro-ferri-nybøite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na(Na₂)(Fe²⁺₃Fe³⁺₂)(Si₈O₂₂)O₂
- Mohs hardness
- 5-6
- Density
- 3.3-3.5 g/cm³
- Colors
- Streak
- Pale Grey
- Luster
- Vitreous
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals
- Cleavage
- Perfect in Two Directions
- Rarity
- Rare
- Uses
- Collector, Scientific Research
- Host rock
- Alkaline Igneous Rocks
- Typical price
- $50-300 per specimen
Where rockhounds find ferro-ferri-nybøite
Classic worldwide localities
- Mont Saint-Hilaire, Canada
- Khibiny Massif, Russia
- Poudrette Quarry, Canada
Field-hunting tip
Look in alkaline igneous rocks country — that is the host setting where ferro-ferri-nybøite typically forms. If you start seeing aegirine, microcline, nepheline in float, you are in the right ground. Field specimens usually show a prismatic crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ferro-ferri-nybøite?+
Where is ferro-ferri-nybøite found?+
How much is ferro-ferri-nybøite worth?+
What rocks look like ferro-ferri-nybøite?+
What minerals are found with ferro-ferri-nybøite?+
What kind of rock does ferro-ferri-nybøite form in?+
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Find ferro-ferri-nybøite on the map
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