Fersmite is a rare niobium-rich mineral that typically forms as small, elongated prismatic crystals in carbonatites and alkaline pegmatites. Collectors often identify it by its dark color, sub-metallic luster, and its characteristic occurrence alongside calcite and other rare-earth minerals.
Is this fersmite?
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 fersmite with a known reference. Fersmite sits at Mohs 4-4.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Fersmite leaves a white to yellowish-white streak.
- 3Read the lusterHold the specimen under a strong light. Fersmite typically shows a vitreous to sub-metallic luster.
- 4Match the color rangeCompare against the expected color range: black, brownish-black, brown.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: prismatic crystals, flattened, often striated.
Often confused with
Fersmite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Columbium Ore is the harder of the two (Mohs 6 vs. 4-4.5); streak differs — Fersmite leaves white to yellowish-white, Columbium Ore leaves dark red to black; luster reads vitreous to sub-metallic on Fersmite and submetallic on Columbium Ore.
How to tell apart: Euxenite is the harder of the two (Mohs 5.5-6.5 vs. 4-4.5); streak differs — Fersmite leaves white to yellowish-white, Euxenite leaves yellowish, grayish, or reddish-brown; luster reads vitreous to sub-metallic on Fersmite and submetallic, resinous, greasy on Euxenite.
Often found alongside fersmite
Minerals reported to co-occur with fersmite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Ca,Ce,Na)(Nb,Ta,Ti)₂(O,OH,F)₆
- Mohs hardness
- 4-4.5
- Density
- 4.7-4.8 g/cm³
- Colors
- Streak
- White to Yellowish-white
- Luster
- Vitreous to Sub-metallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Prismatic Crystals, Flattened, Often Striated
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Carbonatites, Alkaline Pegmatites
- Typical price
- $20-150 for small specimens
Where rockhounds find fersmite
Classic worldwide localities
- Vishnevye Mountains, Russia
- Ravalli County, Montana, USA
- Chaffee County, Colorado, USA
- Madagascar
- Norway
Field-hunting tip
Look in carbonatites, alkaline pegmatites country — that is the host setting where fersmite typically forms. If you start seeing calcite, apatite, phlogopite in float, you are in the right ground. Field specimens usually show a prismatic crystals, flattened, often striated habit, so train your eye for that shape before scanning the outcrop.
Common questions
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How much is fersmite worth?+
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Find fersmite on the map
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