Ferrokentbrooksite is a rare member of the eudialyte group characterized by its iron-dominant composition. It is primarily found in hyper-alkaline intrusive complexes, typically appearing as red to brownish-red grains or small tabular crystals embedded in silicate rocks.
Is this ferrokentbrooksite?
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 ferrokentbrooksite with a known reference. Ferrokentbrooksite 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: red, reddish brown.
- 5Look at form & habitCrystal system: trigonal. Typical habit: equant grains, pseudo octohedral.
Often confused with
Ferrokentbrooksite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside ferrokentbrooksite
Minerals reported to co-occur with ferrokentbrooksite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₁₅Ca₆Fe₃Zr₃Nb(Si₂₅O₇₃)(O,OH,H₂O)₃(F,Cl)₂
- Mohs hardness
- 5-6
- Density
- 3.06 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Trigonal
- Crystal habit
- Equant grains, pseudo octohedral
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A late-stage phase in agpaitic pegmatite dikes in nepheline syenite associated with an alkaline intrusive complex
Where rockhounds find ferrokentbrooksite
Classic worldwide localities
- Poudrette quarry, Mont Saint-Hilaire, Rouville County, Quebec, Canada (type locality)
- Narssârssuk pegmatite, Igaliko alkaline complex, southwestern Greenland
- Langesundfjord area, at Brønnebukta, Siktesøya, Norway
- Barkevik Strand, Norway
- Bjørndalen quarry, Tvedalen, also at Kariåsen in the Sandefjord area, Norway
- Burpala alkaline complex, Baikal area, Russia
Field-hunting tip
Where it forms: A late-stage phase in agpaitic pegmatite dikes in nepheline syenite associated with an alkaline intrusive complex. If you start seeing microcline, nepheline, fluorite in float, you are in the right ground. Typical habit: equant grains, pseudo octohedral. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ferrokentbrooksite?+
Where is ferrokentbrooksite found?+
What rocks look like ferrokentbrooksite?+
What minerals are found with ferrokentbrooksite?+
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What is ferrokentbrooksite used for?+
Find ferrokentbrooksite on the map
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