Allanite is a complex sorosilicate mineral belonging to the epidote group that is commonly found in igneous and metamorphic rocks. It typically appears as dark, opaque, prismatic crystals that are frequently metamict due to internal radiation damage from contained thorium. Collectors should exercise care when handling and storing it due to its mildly radioactive nature.
Is this allanite?
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 allanite with a known reference. Allanite 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. Allanite leaves a gray streak.
- 3Read the lusterHold the specimen under a strong light. Allanite typically shows a submetallic luster.
- 4Match the color rangeCompare against the expected color range: black, brown, reddish-brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals.
Often confused with
Allanite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Allanite leaves gray, Epidote leaves white; luster reads submetallic on Allanite and vitreous on Epidote.
How to tell apart: Tourmaline is the harder of the two (Mohs 7-7.5 vs. 5.5-6); streak differs — Allanite leaves gray, Tourmaline leaves white; luster reads submetallic on Allanite and vitreous on Tourmaline.
How to tell apart: Streak differs — Allanite leaves gray, Hornblende leaves grayish-white; luster reads submetallic on Allanite and vitreous on Hornblende.
Often found alongside allanite
Minerals reported to co-occur with allanite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Ca,Ce,La,Y,Th)₂(Al,Fe³⁺)₃(SiO₄)₃(OH)
- Mohs hardness
- 5.5-6
- Density
- 3.5-4.2 g/cm³
- Colors
- Streak
- Gray
- Luster
- Submetallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals
- Cleavage
- Poor
- Rarity
- Uncommon
- Uses
- Collector, Scientific Research
- Host rock
- Granite Pegmatites, Metamorphic Rocks
- Typical price
- $10-100 per specimen depending on crystal size
Where rockhounds find allanite
8 mapped spotsClassic worldwide localities
- Norway
- Sweden
- USA
- Canada
- Madagascar
Field-hunting tip
Look in granite pegmatites, metamorphic rocks country — that is the host setting where allanite typically forms. If you start seeing quartz, feldspar, biotite in float, you are in the right ground. Field specimens usually show a prismatic crystals habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in North Carolina, Arizona, California — start trip planning there.
Common questions
How do you identify allanite?+
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Find allanite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
