Allanite-(Nd) is a rare member of the epidote group characterized by a dominance of neodymium in the rare-earth element site. It typically occurs as dark, opaque, prismatic crystals in granitic pegmatites and often exhibits metamictization due to internal radioactive decay. Collectors should look for distinct crystalline forms in pegmatitic environments associated with other rare-earth minerals.
Is this allanite-(nd)?
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-(nd) with a known reference. Allanite-(Nd) 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-(Nd) leaves a grayish brown streak.
- 3Read the lusterHold the specimen under a strong light. Allanite-(Nd) typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: black, brown, dark brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, massive, granular.
Often confused with
Allanite-(Nd) vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Allanite-(Nd) leaves grayish brown, Allanite-(Ce) leaves gray; luster reads vitreous on Allanite-(Nd) and submetallic on Allanite-(Ce).
How to tell apart: Streak differs, so Allanite-(Nd) leaves grayish brown, Epidote leaves white.
How to tell apart: Streak differs, so Allanite-(Nd) leaves grayish brown, Allanite leaves gray; luster reads vitreous on Allanite-(Nd) and submetallic on Allanite.
Often found alongside allanite-(nd)
Minerals reported to co-occur with allanite-(nd). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Nd,Ca,Ce)₂(Al,Fe³⁺,Fe²⁺)₃(SiO₄)(Si₂O₇)O(OH)
- Mohs hardness
- 5.5-6
- Density
- 3.5-4.2 g/cm³
- Colors
- Streak
- Grayish Brown
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals, Massive, Granular
- Cleavage
- Imperfect On {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Granite Pegmatites, Syenites, Metamorphic Skarns
Where rockhounds find allanite-(nd)
Classic worldwide localities
- Kola Peninsula, Russia
- Madagascar
- Norway
- Sweden
- United States
Field-hunting tip
Look in granite pegmatites, syenites, metamorphic skarns country, the host setting where allanite-(nd) typically forms. If you start seeing quartz, feldspar, biotite in float, you are in the right ground. Field specimens usually show a prismatic crystals, massive, granular habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify allanite-(nd)?+
Where is allanite-(nd) found?+
Is allanite-(nd) safe to handle?+
What rocks look like allanite-(nd)?+
What minerals are found with allanite-(nd)?+
What kind of rock does allanite-(nd) form in?+
What is allanite-(nd) used for?+
Find allanite-(nd) on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
