Fluorcalcioroméite is a rare member of the pyrochlore supergroup typically found as small, sharp octahedral crystals in manganese-rich metamorphic rocks. It is highly prized by advanced mineral collectors for its distinct symmetry and association with unique mineral assemblages. Collectors should be aware of its toxic antimony content and maintain proper hygiene after physical contact.

Hardness

Mohs

Luster

Vitreous to resinous

Streak

White

Transparency

Translucent

mineralrareRoméite Group family

Fluorcalcioroméite

Hardness: ~5
Luster: Vitreous to resinous
Streak: White
Transparency: Translucent

Is this fluorcalcioroméite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch fluorcalcioroméite with a known reference. Fluorcalcioroméite sits at Mohs ~5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: white.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous to resinous.
4
Match the color range
Compare against the expected color range: yellow, orange.
5
Look at form & habit
Crystal system: cubic. Typical habit: octahedral crystals, massive.

Often confused with

Fluorcalcioroméite vs. its common look-alikes, and how to tell them apart in the field.

mineral

Pyrochlore

Mohs 5-5.5

How to tell apart: Streak differs, so Fluorcalcioroméite leaves white, Pyrochlore leaves brown.

Often found alongside fluorcalcioroméite

Minerals reported to co-occur with fluorcalcioroméite. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: (Ca,Na)₂Sb₂O₆F
Mohs hardness: ~5
Density: 5.113 g/cm³
Colors: Yellow Orange
Streak: White
Luster: Vitreous to resinous
Transparency: Translucent
Crystal system: Cubic
Crystal habit: Octahedral crystals, massive
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: In a structurally deformed manganese deposit most likely of synsedimentary exhalative origin

Where rockhounds find fluorcalcioroméite

Classic worldwide localities

Starlera mine, Ferrera, Hinterrhein district, Grischun, Switzerland

Field-hunting tip

Where it forms: In a structurally deformed manganese deposit most likely of synsedimentary exhalative origin. If you start seeing braunite, hematite, calcite in float, you are in the right ground. Typical habit: octahedral crystals, massive. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify fluorcalcioroméite?+

Mohs hardness is ~5. Luster: vitreous to resinous. The streak is white. Common colors include yellow, orange.

Where is fluorcalcioroméite found?+

Notable localities include Starlera mine, Ferrera, Hinterrhein district, Grischun, Switzerland.

Is fluorcalcioroméite safe to handle?+

Fluorcalcioroméite contains antimony. Contains antimony, which is toxic if ingested or inhaled as dust. Handle with care and wash hands thoroughly after handling specimens.

What rocks look like fluorcalcioroméite?+

Fluorcalcioroméite is most often confused with Pyrochlore, Scheelite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with fluorcalcioroméite?+

Fluorcalcioroméite commonly co-occurs with Braunite, Hematite, Calcite, Quartz, Wallkilldellite-. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does fluorcalcioroméite form in?+

Where it forms: In a structurally deformed manganese deposit most likely of synsedimentary exhalative origin. Working float back to the host body is the standard way to chase a fresh occurrence.

What is fluorcalcioroméite used for?+

Fluorcalcioroméite is used in collector.

Find fluorcalcioroméite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.