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.

Hardness

2.5-3

Mohs

Luster

Pearly

Streak

White

Transparency

Transparent

mineraluncommonMica Group family

Fluorophlogopite

Hardness: 2.5-3
Luster: Pearly
Streak: White
Transparency: Transparent

Is this fluorophlogopite?

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 fluorophlogopite with a known reference. Fluorophlogopite sits at Mohs 2.5-3 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Fluorophlogopite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Fluorophlogopite typically shows a pearly luster.
4
Match the color range
Compare against the expected color range: colorless, white, yellow, brown, green.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: tabular crystals, scaly aggregates, micaceous flakes.

Often confused with

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

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: 2.5-3
Density: 2.7-2.9 g/cm³
Colors: Colorless White Yellow Brown Green
Streak: White
Luster: Pearly
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Tabular Crystals, Scaly Aggregates, Micaceous Flakes
Cleavage: Perfect Basal
Rarity: Uncommon
Uses: Industrial, Collector
Host rock: Metamorphosed Limestones, Skarns, Alkaline Igneous Rocks
Typical price: $10-60 thumbnail

Where rockhounds find fluorophlogopite

Classic worldwide localities

Kola Peninsula, Russia
Franklin, New Jersey, USA
Monte Somma, Italy
Kilimanjaro, Tanzania

Field-hunting tip

Look in metamorphosed limestones, skarns, alkaline igneous rocks country — that is the host setting where fluorophlogopite typically forms. If you start seeing calcite, diopside, forsterite in float, you are in the right ground. Field specimens usually show a tabular crystals, scaly aggregates, micaceous flakes habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify fluorophlogopite?+

Mohs hardness is 2.5-3. It typically shows a pearly luster. The streak is white. Common colors include colorless, white, yellow, brown.

Where is fluorophlogopite found?+

Notable localities include Kola Peninsula, Russia; Franklin, New Jersey, USA; Monte Somma, Italy; Kilimanjaro, Tanzania.

How much is fluorophlogopite worth?+

Typical asking prices fall in the range of $10-60 thumbnail. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like fluorophlogopite?+

Fluorophlogopite is most often confused with Phlogopite, Muscovite, Biotite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with fluorophlogopite?+

Fluorophlogopite commonly co-occurs with Calcite, Diopside, Forsterite, Chondrodite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does fluorophlogopite form in?+

Fluorophlogopite typically forms in metamorphosed limestones, skarns, alkaline igneous rocks. Working float back to the host body is the standard way to chase a fresh occurrence.

What is fluorophlogopite used for?+

Fluorophlogopite is used in industrial, collector.

Find fluorophlogopite on the map

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