Niobophyllite is a rare member of the astrophyllite group, distinguished primarily by its high niobium content. It forms distinct golden-bronze bladed or star-shaped aggregates, often found embedded in alkaline igneous rocks. Collectors prize it for its unique habit and similarity to the more common astrophyllite.
Is this niobophyllite?
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 niobophyllite with a known reference. Niobophyllite sits at Mohs 3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Niobophyllite leaves a yellowish-brown streak.
- 3Read the lusterHold the specimen under a strong light. Niobophyllite typically shows a pearly luster.
- 4Match the color rangeCompare against the expected color range: bronze-brown, golden-brown, dark brown.
- 5Look at form & habitCrystal system: triclinic. Typical habit: bladed, platy, radiating or stellate aggregates.
Often confused with
Niobophyllite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Niobophyllite leaves yellowish-brown, Astrophyllite leaves golden-brown; luster reads pearly on Niobophyllite and submetallic on Astrophyllite.
How to tell apart: Streak differs, so Niobophyllite leaves yellowish-brown, Kupletskite leaves brown; luster reads pearly on Niobophyllite and submetallic on Kupletskite.
Often found alongside niobophyllite
Minerals reported to co-occur with niobophyllite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (K,Na)₃(Fe,Mn)₇(Nb,Ti)₂Si₈O₂₆(OH)₄F
- Mohs hardness
- 3
- Density
- 3.37 g/cm³
- Streak
- Yellowish-brown
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Triclinic
- Crystal habit
- Bladed, Platy, Radiating or Stellate Aggregates
- Cleavage
- Perfect On {001}
- Rarity
- Rare
- Uses
- Collector, Scientific Research
- Host rock
- Alkaline Igneous Rocks, Pegmatites
- Typical price
- $20-150 per specimen depending on size and crystal quality
Where rockhounds find niobophyllite
Classic worldwide localities
- Kola Peninsula, Russia
- Mont Saint-Hilaire, Canada
- Greenland
Field-hunting tip
Look in alkaline igneous rocks, pegmatites country, the host setting where niobophyllite typically forms. If you start seeing aegirine, microcline, nepheline in float, you are in the right ground. Field specimens usually show a bladed, platy, radiating or stellate aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find niobophyllite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
