Mantienneite is a rare phosphate mineral typically occurring as small, bipyramidal yellow crystals. It is primarily found in complex granite pegmatites and is highly prized by advanced mineral collectors for its scarcity and distinct crystal form.

Hardness

2-3

Mohs

Luster

Vitreous

Streak

Pale brown with a rose tint

Transparency

Translucent

mineralrareWardite Group family

Mantienneite

Hardness: 2-3
Luster: Vitreous
Streak: Pale brown with a rose tint
Transparency: Translucent

Is this mantienneite?

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 mantienneite with a known reference. Mantienneite sits at Mohs 2-3, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: pale brown with a rose tint.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: yellow brown.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: bipyramidal crystals.

Often confused with

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

mineral

Wardite

Mohs 5

How to tell apart: Wardite is the harder of the two (Mohs 5 vs. 2-3); streak differs, so Mantienneite leaves pale brown with a rose tint, Wardite leaves white.

How to tell apart: Childrenite is the harder of the two (Mohs 5 vs. 2-3); streak differs, so Mantienneite leaves pale brown with a rose tint, Childrenite leaves white.

Compare →

Often found alongside mantienneite

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

All properties

Chemical formula: (H₂O)₂Mg₂(Al₂Ti)(PO₄)₄(OH)₂(H₂O)₁₀·4H₂O
Mohs hardness: 2-3
Density: 2.31 g/cm³
Colors: Yellow brown
Streak: Pale brown with a rose tint
Luster: Vitreous
Transparency: Translucent
Crystal system: Orthorhombic
Crystal habit: Bipyramidal crystals
Cleavage: Perfect on {001}; poor on {010}
Rarity: Rare
Uses: Collector
Host rock: Replacing minerals in and forming the matrix of sandy layers in lacustrine shale

Where rockhounds find mantienneite

Classic worldwide localities

Anloua, near Ngaoundéré, Cameroon

Field-hunting tip

Where it forms: Replacing minerals in and forming the matrix of sandy layers in lacustrine shale. If you start seeing kaolinite, siderite, quartz in float, you are in the right ground. Typical habit: bipyramidal crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify mantienneite?+

Mohs hardness is 2-3. Luster: vitreous. The streak is pale brown with a rose tint. Common colors include yellow brown.

Where is mantienneite found?+

Notable localities include Anloua, near Ngaoundéré, Cameroon.

What rocks look like mantienneite?+

Mantienneite is most often confused with Wardite, Childrenite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with mantienneite?+

Mantienneite commonly co-occurs with Kaolinite, Siderite, Quartz, Vivianite, Organic matter. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does mantienneite form in?+

Where it forms: Replacing minerals in and forming the matrix of sandy layers in lacustrine shale. Working float back to the host body is the standard way to chase a fresh occurrence.

What is mantienneite used for?+

Mantienneite is used in collector.

Find mantienneite on the map

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