Clinofergusonite-(Y) is a rare monoclinic rare-earth niobate that occurs primarily in granite pegmatites. Collectors often identify it by its prismatic, often metamict crystal habit and its association with other rare earth minerals, though it typically requires X-ray diffraction to distinguish from the tetragonal fergusonite-(Y).
Is this clinofergusonite-(y)?
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 clinofergusonite-(y) with a known reference. Clinofergusonite-(Y) sits at Mohs 5.5-6.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: submetallic.
- 4Match the color rangeCompare against the expected color range: yellow, brown, black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals.
Often confused with
Clinofergusonite-(Y) vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Clinofergusonite-(Y) leaves pale yellow, Fergusonite-(Y) leaves brown, yellow-brown, greenish gray; luster reads submetallic on Clinofergusonite-(Y) and dull; vitreous to submetallic on fractures on Fergusonite-(Y).
How to tell apart: Streak differs, so Clinofergusonite-(Y) leaves pale yellow, Euxenite-(Y) leaves yellowish, grayish, or reddish brown; luster reads submetallic on Clinofergusonite-(Y) and brilliant submetallic, waxy to resinous on fractures on Euxenite-(Y).
Often found alongside clinofergusonite-(y)
Minerals reported to co-occur with clinofergusonite-(y). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- YNbO₄
- Mohs hardness
- 5.5-6.5
- Density
- 5.6-5.8 g/cm³
- Streak
- Pale yellow
- Luster
- Submetallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- granite pegmatites
Where rockhounds find clinofergusonite-(y)
Classic worldwide localities
- Sweden
- Norway
- Canada
- Russia
- China
Field-hunting tip
Where it forms: granite pegmatites. If you start seeing zircon, allanite, monazite in float, you are in the right ground. Typical habit: prismatic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify clinofergusonite-(y)?+
Where is clinofergusonite-(y) found?+
Is clinofergusonite-(y) safe to handle?+
What rocks look like clinofergusonite-(y)?+
What minerals are found with clinofergusonite-(y)?+
What kind of rock does clinofergusonite-(y) form in?+
What is clinofergusonite-(y) used for?+
Find clinofergusonite-(y) on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
