Freudenbergite is a rare sodium iron titanate mineral found primarily in alkaline igneous environments. It typically appears as small, dark brown to black tabular crystals and is prized by advanced mineral collectors for its scarcity and unique chemical composition.
Is this freudenbergite?
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 freudenbergite with a known reference. Freudenbergite 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. Freudenbergite leaves a yellowish-brown streak.
- 3Read the lusterHold the specimen under a strong light. Freudenbergite typically shows a submetallic luster.
- 4Match the color rangeCompare against the expected color range: brown, black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals.
Often confused with
Freudenbergite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Freudenbergite leaves yellowish-brown, Manaccanite leaves black.
How to tell apart: Streak differs — Freudenbergite leaves yellowish-brown, Iron Ore leaves reddish-brown to black; luster reads submetallic on Freudenbergite and metallic to submetallic on Iron Ore.
Often found alongside freudenbergite
Minerals reported to co-occur with freudenbergite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₂Fe₄Ti₆O₁₉
- Mohs hardness
- 5-6
- Density
- 4.45 g/cm³
- Streak
- Yellowish-brown
- Luster
- Submetallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Alkaline Igneous Rocks
- Typical price
- $50-200 thumbnail
Where rockhounds find freudenbergite
Classic worldwide localities
- Freudenberg, Germany
- Saint-Amable sill, Canada
Field-hunting tip
Look in alkaline igneous rocks country — that is the host setting where freudenbergite typically forms. If you start seeing nepheline, aegirine, magnetite in float, you are in the right ground. Field specimens usually show a tabular crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find freudenbergite on the map
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