Oxyphlogopite is a rare member of the mica group characterized by the substitution of hydroxyl ions by oxygen, typically resulting from oxidation in high-temperature volcanic environments. It is physically similar to common phlogopite but can often be distinguished by its deeper reddish-brown hues and specific geological occurrence within volcanic ejecta.

Hardness

2.5-3

Mohs

Luster

Pearly

Streak

White

Transparency

Translucent

mineralrarePhlogopite family

Oxyphlogopite

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

No image

Is this oxyphlogopite?

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 oxyphlogopite with a known reference. Oxyphlogopite 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. Oxyphlogopite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Oxyphlogopite typically shows a pearly luster.
4
Match the color range
Compare against the expected color range: brown, reddish-brown, dark-brown.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: tabular crystals, scaly aggregates, disseminated flakes.

Often confused with

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

Often found alongside oxyphlogopite

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

All properties

Chemical formula: K(Mg,Fe³⁺)₃(AlSi₃O₁₀)(OH,O)₂
Mohs hardness: 2.5-3
Density: 2.8-3.0 g/cm³
Colors: Brown Reddish-brown Dark-brown
Streak: White
Luster: Pearly
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Tabular Crystals, Scaly Aggregates, Disseminated Flakes
Cleavage: Perfect Basal
Rarity: Rare
Uses: Collector, Scientific Research
Host rock: Alkaline Igneous Rocks, Carbonatites
Typical price: $20-100 per specimen

Where rockhounds find oxyphlogopite

Classic worldwide localities

Monte Somma, Italy
Khibiny Massif, Russia
Kola Peninsula, Russia

Field-hunting tip

Look in alkaline igneous rocks, carbonatites country — that is the host setting where oxyphlogopite typically forms. If you start seeing sanidine, nepheline, leucite in float, you are in the right ground. Field specimens usually show a tabular crystals, scaly aggregates, disseminated flakes habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify oxyphlogopite?+

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

Where is oxyphlogopite found?+

Notable localities include Monte Somma, Italy; Khibiny Massif, Russia; Kola Peninsula, Russia.

How much is oxyphlogopite 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 oxyphlogopite?+

Oxyphlogopite 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 oxyphlogopite?+

Oxyphlogopite commonly co-occurs with Sanidine, Nepheline, Leucite, Augite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does oxyphlogopite form in?+

Oxyphlogopite 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 oxyphlogopite used for?+

Oxyphlogopite is used in collector, scientific research.

Find oxyphlogopite on the map

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