Fluorchegemite is a very rare silicate mineral found in the contact metamorphic zones of volcanic calderas. It is structurally similar to chegemite but distinguished by its fluorine content, typically occurring as small, inconspicuous grains within complex skarn assemblages.
Is this fluorchegemite?
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 fluorchegemite with a known reference. Fluorchegemite 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. Fluorchegemite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Fluorchegemite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white, pale yellow.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: anhedral to subhedral grains.
Often confused with
Fluorchegemite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside fluorchegemite
Minerals reported to co-occur with fluorchegemite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₇(SiO₄)₃F₂
- Mohs hardness
- 5.5
- Density
- 2.86 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Anhedral to Subhedral Grains
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Skarn and Altered Carbonate Xenoliths in Ignimbrite
- Typical price
- n/a (extremely rare specimen, value determined by research institutions)
Where rockhounds find fluorchegemite
Classic worldwide localities
- Upper Chegem volcanic caldera, Kabardino-Balkaria, Russia
Field-hunting tip
Look in skarn and altered carbonate xenoliths in ignimbrite country — that is the host setting where fluorchegemite typically forms. If you start seeing chegemite, wadalite, reinhardbraunsite in float, you are in the right ground. Field specimens usually show a anhedral to subhedral grains habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify fluorchegemite?+
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Find fluorchegemite on the map
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