Fenaksite is a rare potassium-sodium-iron silicate found primarily in hyper-alkaline igneous complexes. Collectors usually seek it in its characteristic pink to reddish-brown tabular crystal form within pegmatite environments.
Is this fenaksite?
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 fenaksite with a known reference. Fenaksite 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. Fenaksite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Fenaksite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: pink, reddish-brown.
- 5Look at form & habitCrystal system: triclinic. Typical habit: tabular crystals, massive, granular.
Often confused with
Fenaksite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside fenaksite
Minerals reported to co-occur with fenaksite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- KNaFe²⁺Si₄O₁₀
- Mohs hardness
- 5-6
- Density
- 2.84 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Triclinic
- Crystal habit
- Tabular Crystals, Massive, Granular
- Cleavage
- Good On {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Alkaline Igneous Rocks, Pegmatites
- Typical price
- $50-300 per specimen depending on size and quality
Where rockhounds find fenaksite
Classic worldwide localities
- Khibiny Massif, Kola Peninsula, Russia
- Mont Saint-Hilaire, Quebec, Canada
Field-hunting tip
Look in alkaline igneous rocks, pegmatites country, the host setting where fenaksite typically forms. If you start seeing aegirine, nepheline, microcline in float, you are in the right ground. Field specimens usually show a tabular crystals, massive, granular habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find fenaksite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
