Fersmanite is a rare titanium-rich silicate mineral found primarily in the complex alkaline rocks of the Kola Peninsula. It is typically identified by its distinct wedge-shaped to tabular crystals often associated with other rare alkaline minerals like eudialyte and aegirine.
Is this fersmanite?
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 fersmanite with a known reference. Fersmanite 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. Streak: white with pale brownish tint.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: golden yellow, resin brown, light brown, dark brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: pseudo tetragonal.
Often confused with
Fersmanite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Fersmanite is noticeably harder (Mohs 5-5.5 vs. 2-3); streak differs, so Fersmanite leaves white with pale brownish tint, Lamprophyllite leaves pale yellow, may have an orange tint; luster reads vitreous on Fersmanite and submetallic on cleavages on Lamprophyllite.
How to tell apart: Fersmanite is noticeably harder (Mohs 5-5.5 vs. 3); streak differs, so Fersmanite leaves white with pale brownish tint, Astrophyllite leaves golden; luster reads vitreous on Fersmanite and submetallic, pearly, greasy on Astrophyllite.
How to tell apart: Streak differs, so Fersmanite leaves white with pale brownish tint, Wöhlerite leaves pale yellow.
Often found alongside fersmanite
Minerals reported to co-occur with fersmanite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₄(Na,Ca)₄(Ti,Nb)₄(Si₂O₇)₂O₈F₃
- Mohs hardness
- 5-5.5
- Density
- 3.44-3.46 g/cm³
- Colors
- Streak
- White with pale brownish tint
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Pseudo tetragonal
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- In aegirine-rich nepheline pegmatites in a differentiated alkalic massif (Khibiny massif, Russia)
Where rockhounds find fersmanite
Classic worldwide localities
- Mt. Eveslogchorr, Khibiny massif, Kola Peninsula, Russia
- Poços de Caldas massif, Minas Gerais, Brazil
Field-hunting tip
Where it forms: In aegirine-rich nepheline pegmatites in a differentiated alkalic massif (Khibiny massif, Russia). If you start seeing feldspar, pectolite, apatite in float, you are in the right ground. Typical habit: pseudo tetragonal. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify fersmanite?+
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What rocks look like fersmanite?+
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Find fersmanite on the map
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