Fluornatromicrolite is a rare member of the pyrochlore supergroup characterized by high sodium and fluorine content in its structure. It typically occurs as small, sharp octahedral crystals in rare alkaline igneous environments. Collectors should be aware of its inherent radioactivity due to common substitution of radioactive elements within the crystal lattice.
Is this fluornatromicrolite?
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 fluornatromicrolite with a known reference. Fluornatromicrolite sits at Mohs 5-5.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Fluornatromicrolite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Fluornatromicrolite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, brown, orange, colorless.
- 5Look at form & habitCrystal system: cubic. Typical habit: octahedral crystals.
Often found alongside fluornatromicrolite
Minerals reported to co-occur with fluornatromicrolite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Na,Ca,◻)₂Ta₂O₆F
- Mohs hardness
- 5-5.5
- Density
- 4.9-5.1 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Cubic
- Crystal habit
- Octahedral Crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Agpaitic Syenites and Pegmatites
- Typical price
- $50-500 depending on specimen quality and size
Where rockhounds find fluornatromicrolite
Classic worldwide localities
- Ilímaussaq complex, Greenland
- St. Hilaire, Quebec, Canada
Field-hunting tip
Look in agpaitic syenites and pegmatites country — that is the host setting where fluornatromicrolite typically forms. If you start seeing eudialyte, aegirine, sodalite in float, you are in the right ground. Field specimens usually show a octahedral crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find fluornatromicrolite on the map
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