Fluoro-nybøite is an exceptionally rare sodium-rich amphibole characterized by its distinct blue to violet hues. It typically forms within high-pressure metamorphic environments, occurring as prismatic crystals or fibrous masses embedded in host metamorphic assemblages.
Is this fluoro-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 fluoro-nybøite with a known reference. Fluoro-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. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: blue, violet, greenish-blue.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, fibrous, granular.
Often confused with
Fluoro-nybøite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Fluoro-nybøite leaves white, Glaucophane leaves blue-gray.
How to tell apart: Streak differs, so Fluoro-nybøite leaves white, Riebeckite leaves greenish brown.
How to tell apart: Streak differs, so Fluoro-nybøite leaves white, Arfvedsonite leaves deep bluish gray, gray-green.
Often found alongside fluoro-nybøite
Minerals reported to co-occur with fluoro-nybøite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaNa₂(Mg₃Al₂)(Si₇Al)O₂₂F₂
- Mohs hardness
- 5-6
- Density
- 3.3-3.4 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic crystals, fibrous, granular
- Cleavage
- Perfect prismatic
- Rarity
- Rare
- Uses
- Collector
- Host rock
- metamorphic rocks, specifically eclogites and high-pressure amphibolites
Where rockhounds find fluoro-nybøite
Classic worldwide localities
- Nybø, Norway
- Kvinesdal, Norway
- Mianwali, Pakistan
Field-hunting tip
Where it forms: metamorphic rocks, specifically eclogites and high-pressure amphibolites. If you start seeing albite, apatite, quartz in float, you are in the right ground. Typical habit: prismatic crystals, fibrous, granular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify fluoro-nybøite?+
Where is fluoro-nybøite found?+
What rocks look like fluoro-nybøite?+
What minerals are found with fluoro-nybøite?+
What kind of rock does fluoro-nybøite form in?+
What is fluoro-nybøite used for?+
Find fluoro-nybøite on the map
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