Fluorotetraferriphlogopite is a rare mica-group mineral occurring primarily in carbonatites and alkaline igneous environments. Collectors identify it by its characteristic platy, micaceous habit and distinctive iron-rich brown coloration typical of the phlogopite-annite series.

Hardness

2.5-3

Mohs

Luster

Pearly

Streak

White

Transparency

Translucent

mineralrareMica Group family

Fluorotetraferriphlogopite

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

No image

Is this fluorotetraferriphlogopite?

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 fluorotetraferriphlogopite with a known reference. Fluorotetraferriphlogopite 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. Fluorotetraferriphlogopite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Fluorotetraferriphlogopite typically shows a pearly luster.
4
Match the color range
Compare against the expected color range: brown, yellowish-brown, dark brown.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: platy crystals, micaceous masses.

Often confused with

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

Often found alongside fluorotetraferriphlogopite

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

All properties

Chemical formula: KFe²⁺₃(Si₃Fe³⁺)O₁₀F₂
Mohs hardness: 2.5-3
Density: 2.8-3.0 g/cm³
Colors: Brown Yellowish-brown Dark Brown
Streak: White
Luster: Pearly
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Platy Crystals, Micaceous Masses
Cleavage: Perfect Basal
Rarity: Rare
Uses: Collector
Host rock: Alkaline Igneous Rocks, Carbonatites
Typical price: $20-100 per specimen

Where rockhounds find fluorotetraferriphlogopite

Classic worldwide localities

Kovdor Massif (Russia)
Iron Mountain (USA)

Field-hunting tip

Look in alkaline igneous rocks, carbonatites country — that is the host setting where fluorotetraferriphlogopite typically forms. If you start seeing magnetite, apatite, calcite in float, you are in the right ground. Field specimens usually show a platy crystals, micaceous masses habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify fluorotetraferriphlogopite?+

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

Where is fluorotetraferriphlogopite found?+

Notable localities include Kovdor Massif (Russia); Iron Mountain (USA).

How much is fluorotetraferriphlogopite worth?+

Typical asking prices fall in the range of $20-100 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like fluorotetraferriphlogopite?+

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

What minerals are found with fluorotetraferriphlogopite?+

Fluorotetraferriphlogopite commonly co-occurs with Magnetite, Apatite, Calcite, Forsterite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does fluorotetraferriphlogopite form in?+

Fluorotetraferriphlogopite typically forms in alkaline igneous rocks, carbonatites. Working float back to the host body is the standard way to chase a fresh occurrence.

What is fluorotetraferriphlogopite used for?+

Fluorotetraferriphlogopite is used in collector.

Find fluorotetraferriphlogopite on the map

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