Aspedamite is a rare iron niobium thorium hydroxide, typically brownish orange to deep red. It occurs in a complex granitic pegmatite on altered monazite. It was first described from Herrebøkasa quarry, 2 km north-northeast of Aspedammen, Østfold county, Norway.
Is this aspedamite?
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 aspedamite with a known reference. Aspedamite sits at Mohs 3-4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: very pale orange.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine.
- 4Match the color rangeCompare against the expected color range: brownish orange, deep red.
- 5Look at form & habitCrystal system: cubic. Typical habit: massive.
Often confused with
Aspedamite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Allanite is the harder of the two (Mohs 5.5-6 vs. 3-4); streak differs, so Aspedamite leaves very pale orange, Allanite leaves gray; luster reads adamantine on Aspedamite and submetallic on Allanite.
How to tell apart: Epidote is the harder of the two (Mohs 6-7 vs. 3-4); streak differs, so Aspedamite leaves very pale orange, Epidote leaves grayish white; luster reads adamantine on Aspedamite and vitreous, pearly, somewhat resinous on Epidote.
Often found alongside aspedamite
Minerals reported to co-occur with aspedamite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- ☐₁₂(Fe³⁺,Fe²⁺)₃Nb₄[Th(Nb,Fe³⁺)₁₂O₄₂][(H₂O),(OH)]₁₂
- Mohs hardness
- 3-4
- Density
- 4.070 g/cm³
- Colors
- Brownish orangeDeep red
- Streak
- Very pale orange
- Luster
- Adamantine
- Transparency
- Transparent
- Crystal system
- Cubic
- Crystal habit
- Massive
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In a complex granitic pegmatite on altered monazite
Where rockhounds find aspedamite
Classic worldwide localities
- Herrebøkasa quarry, 2 km north-northeast of Aspedammen, Østfold county, Norway
Field-hunting tip
Where it forms: In a complex granitic pegmatite on altered monazite. If you start seeing monazite in float, you are in the right ground. Typical habit: massive. Train your eye for that shape before scanning the outcrop.
Common questions
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Find aspedamite on the map
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