Fluorbritholite-(Y) is a rare rare-earth silicate mineral belonging to the apatite supergroup. It is typically found as small, prismatic, brownish to yellow crystals in alkaline pegmatite environments and is often slightly radioactive due to thorium or uranium substitutions.
Is this fluorbritholite-(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 fluorbritholite-(y) with a known reference. Fluorbritholite-(Y) sits at Mohs 5.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale brown to almost white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to greasy; resinous [metamict].
- 4Match the color rangeCompare against the expected color range: brown-pink, dark brown.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: prismatic crystals, massive.
Often confused with
Fluorbritholite-(Y) vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Fluorbritholite-(Y) leaves pale brown to almost white, Apatite leaves white.
How to tell apart: Streak differs, so Fluorbritholite-(Y) leaves pale brown to almost white, Britholite-(Ce) leaves white; luster reads vitreous to greasy; resinous [metamict] on Fluorbritholite-(Y) and adamantine on Britholite-(Ce).
How to tell apart: Streak differs, so Fluorbritholite-(Y) leaves pale brown to almost white, Steenstrupine-(Ce) leaves brownish, nearly white; luster reads vitreous to greasy; resinous [metamict] on Fluorbritholite-(Y) and dull on Steenstrupine-(Ce).
Often found alongside fluorbritholite-(y)
Minerals reported to co-occur with fluorbritholite-(y). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Y,Ca)₅(SiO₄)₃F
- Mohs hardness
- 5.5
- Density
- 4.609 g/cm³
- Colors
- Brown-pinkDark brown
- Streak
- Pale brown to almost white
- Luster
- Vitreous to greasy; resinous [metamict]
- Transparency
- Transparent
- Crystal system
- Hexagonal
- Crystal habit
- Prismatic crystals, massive
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In pegmatite cutting alkaline granite
Where rockhounds find fluorbritholite-(y)
Classic worldwide localities
- Lagmannsvik and Kråkmo, Hamarøy, Nordland, Norway, and at Mt. Vyuntspakhk, Western Keivy, Kola Peninsula, Russia
Field-hunting tip
Where it forms: In pegmatite cutting alkaline granite. If you start seeing y-bearing fluorite, allanite-, quartz in float, you are in the right ground. Typical habit: prismatic crystals, massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify fluorbritholite-(y)?+
Where is fluorbritholite-(y) found?+
Is fluorbritholite-(y) safe to handle?+
What rocks look like fluorbritholite-(y)?+
What minerals are found with fluorbritholite-(y)?+
What kind of rock does fluorbritholite-(y) form in?+
What is fluorbritholite-(y) used for?+
Find fluorbritholite-(y) on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
