Allanite-(Ce) is a characteristic member of the epidote group, frequently found as dark, opaque, prismatic crystals in pegmatitic environments. It is highly valued by collectors for its radioactive properties and complex rare-earth element chemistry.
Is this allanite-(ce)?
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-(ce) with a known reference. Allanite-(Ce) 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. Streak: gray.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous, resinous to submetallic.
- 4Match the color rangeCompare against the expected color range: black, brown, reddish brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: disseminated, massive.
Often confused with
Allanite-(Ce) vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Allanite-(Ce) leaves gray, Epidote leaves grayish white.
How to tell apart: Streak differs, so Allanite-(Ce) leaves gray, Zoisite leaves white.
How to tell apart: Streak differs, so Allanite-(Ce) leaves gray, Monazite leaves white; luster reads vitreous, resinous to submetallic on Allanite-(Ce) and resinous on Monazite.
Often found alongside allanite-(ce)
Minerals reported to co-occur with allanite-(ce). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaCeAl₂Fe(Si₂O₇)(SiO₄)O(OH)
- Mohs hardness
- 5.5-6
- Density
- 3.5-4.2 g/cm³
- Colors
- Streak
- Gray
- Luster
- Vitreous, resinous to submetallic
- Transparency
- Translucent to opaque
- Crystal system
- Monoclinic
- Crystal habit
- Disseminated, massive
- Cleavage
- Imperfect on {001}; poor on {100} and {110}
- Rarity
- Uncommon
- Uses
- Collector, Geological study
- Host rock
- An accessory in some granites and granite pegmatites, syenites, more rarely in gabbroic pegmatites
Where rockhounds find allanite-(ce)
Classic worldwide localities
- Pacoima Canyon, Los Angeles Co., California, USA
- Baringer Hill pegmatite, 26 km west of Burnet, and on the Rode Ranch, Llano Co., Texas, USA
- Qáqarssuatsiaq, Alluk, south Greenland
- Ytterby and Finbo, Sweden
- Kragerö, Arendal, and on Hitterö Island, Flekkefjord, Norway
- Sillböle, Stansvik, and Vaarala, Finland
Field-hunting tip
Where it forms: An accessory in some granites and granite pegmatites, syenites, more rarely in gabbroic pegmatites. If you start seeing epidote, muscovite, fluorite in float, you are in the right ground. Typical habit: disseminated, massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify allanite-(ce)?+
Where is allanite-(ce) found?+
Is allanite-(ce) safe to handle?+
What rocks look like allanite-(ce)?+
What minerals are found with allanite-(ce)?+
What kind of rock does allanite-(ce) form in?+
What is allanite-(ce) used for?+
Find allanite-(ce) on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
