Fluorophlogopite is a fluorine-rich member of the mica group, characterized by its flexible, thin lamellae and pearly luster. It commonly appears in metamorphosed carbonate rocks and is visually indistinguishable from standard phlogopite without advanced chemical analysis. Collectors typically find it in contact metamorphic zones alongside other high-temperature silicates.
Is this fluorophlogopite?
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 fluorophlogopite with a known reference. Fluorophlogopite sits at Mohs 2-3, 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.
- 4Match the color rangeCompare against the expected color range: pale yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy.
Often confused with
Fluorophlogopite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads vitreous to greasy on Fluorophlogopite and pearly to submetallic on cleavage on Phlogopite.
How to tell apart: Luster reads vitreous to greasy on Fluorophlogopite and splendent to submetallic, vitreous, pearly on cleavage on Biotite.
Often found alongside fluorophlogopite
Minerals reported to co-occur with fluorophlogopite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- KMg₃(AlSi₃O₁₀)F₂
- Mohs hardness
- 2-3
- Density
- 2.7-2.9 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous to greasy
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Platy
- Cleavage
- Perfect on {001}
- Rarity
- Uncommon
- Uses
- Industrial, Collector
- Host rock
- Occurs within interstitial, friable altered material in lava fissures and breccias
Where rockhounds find fluorophlogopite
Classic worldwide localities
- Southwest flank of the Etnean Volcanic Complex, Biancavilla, Catania, Mt. Etna, Sicily, Italy (type locality)
Field-hunting tip
Where it forms: Occurs within interstitial, friable altered material in lava fissures and breccias. If you start seeing calcite, diopside, forsterite in float, you are in the right ground. Typical habit: platy. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify fluorophlogopite?+
Where is fluorophlogopite found?+
What rocks look like fluorophlogopite?+
What minerals are found with fluorophlogopite?+
What kind of rock does fluorophlogopite form in?+
What is fluorophlogopite used for?+
Find fluorophlogopite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
