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 — that is 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.
