Aspedamite is a rare, radioactive member of the allanite group that typically presents as massive, dark-colored grains within pegmatites. It is primarily found at its type locality in Aspedam, Norway, and is valued by specialist collectors of radioactive and rare-earth minerals.
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 5.5-6 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Aspedamite leaves a brownish streak.
- 3Read the lusterHold the specimen under a strong light. Aspedamite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: brown, black.
- 5Look at form & habitCrystal system: monoclinic. 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: Streak differs — Aspedamite leaves brownish, Allanite leaves gray; luster reads vitreous on Aspedamite and submetallic on Allanite.
How to tell apart: Streak differs — Aspedamite leaves brownish, Epidote leaves white.
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
- CaREEFe³⁺AlFe²⁺Si₃O₁₂(OH)
- Mohs hardness
- 5.5-6
- Density
- 4.2-4.3 g/cm³
- Streak
- Brownish
- Luster
- Vitreous
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Massive
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Pegmatites
- Typical price
- $20-100 per specimen
Where rockhounds find aspedamite
Classic worldwide localities
- Aspedam, Østfold, Norway
Field-hunting tip
Look in pegmatites country — that is the host setting where aspedamite typically forms. If you start seeing microcline, quartz, biotite in float, you are in the right ground. Field specimens usually show a massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify aspedamite?+
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How much is aspedamite worth?+
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What rocks look like aspedamite?+
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Find aspedamite on the map
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