Fluorcalciobritholite is a rare silicate member of the apatite supergroup typically found in alkaline syenites and pegmatites. Collectors look for its characteristic prismatic crystal habit and association with other rare alkaline minerals, though it is often identified primarily through chemical analysis due to its visual similarity to standard apatite.
Is this fluorcalciobritholite?
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 fluorcalciobritholite with a known reference. Fluorcalciobritholite 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: 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, pale pinkish brown.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: hexagonal, prismatic.
Often confused with
Fluorcalciobritholite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside fluorcalciobritholite
Minerals reported to co-occur with fluorcalciobritholite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Ca,REE)₅(SiO₄,PO₄)₃F
- Mohs hardness
- 5.5
- Density
- 4.2 g/cm³
- Colors
- BrownPale pinkish brown
- Streak
- White
- Luster
- Vitreous to greasy; resinous (metamict)
- Transparency
- Transparent
- Crystal system
- Hexagonal
- Crystal habit
- Hexagonal, prismatic
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In veinlets cross-cutting fenitized gneiss xenoliths in foyaite (Khibiny)
Where rockhounds find fluorcalciobritholite
Classic worldwide localities
- Eastern slope of Mount Kukisvumchorr, at the source of the Tuliok river, Khibiny alkaline complex, Kola Peninsula, Russia
- Sol’skoye REE deposit, Burpala and Ulan-Erge alkaline massifs, Siberia, Russia
Field-hunting tip
Where it forms: In veinlets cross-cutting fenitized gneiss xenoliths in foyaite (Khibiny). If you start seeing orthoclase, nepheline, sodalite in float, you are in the right ground. Typical habit: hexagonal, prismatic. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify fluorcalciobritholite?+
Where is fluorcalciobritholite found?+
Is fluorcalciobritholite safe to handle?+
What rocks look like fluorcalciobritholite?+
What minerals are found with fluorcalciobritholite?+
What kind of rock does fluorcalciobritholite form in?+
What is fluorcalciobritholite used for?+
Find fluorcalciobritholite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
