Thérèsemagnanite is a rare cobalt-bearing sulfate mineral typically found as delicate, pink to pale pink platy crystals or crusts. It is primarily known from the historic cobalt mining district of Bou Azzer in Morocco, where it forms as a secondary mineral in oxidation zones.

Hardness

1.5-2

Mohs

Luster

Pearly

Streak

Pale pink

Transparency

Transparent

mineralrareCobalt-bearing minerals family

Thérèsemagnanite

Hardness: 1.5-2
Luster: Pearly
Streak: Pale pink
Transparency: Transparent

Is this thérèsemagnanite?

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 thérèsemagnanite with a known reference. Thérèsemagnanite sits at Mohs 1.5-2, 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 pink.
3
Read the luster
Hold the specimen under a strong light. Luster: pearly.
4
Match the color range
Compare against the expected color range: pink, light pink.
5
Look at form & habit
Crystal system: hexagonal. Typical habit: platy, spherical, thin.

Often confused with

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

mineral

Woodwardite

Mohs 1.5-2.5

How to tell apart: Streak differs, so Thérèsemagnanite leaves pale pink, Woodwardite leaves light blue.

Compare →

Often found alongside thérèsemagnanite

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

All properties

Chemical formula: NaCo₄(SO₄)(OH)₆Cl·6H₂O
Mohs hardness: 1.5-2
Density: 2.52 g/cm³
Colors: Pink Light pink
Streak: Pale pink
Luster: Pearly
Transparency: Transparent
Crystal system: Hexagonal
Crystal habit: Platy, spherical, thin
Cleavage: Perfect on {0001}
Rarity: Rare
Uses: Collector
Host rock: A secondary mineral in the oxidized portions of a polymetallic sulfide deposit

Where rockhounds find thérèsemagnanite

Classic worldwide localities

Cap Garonne mine, near le Pradet, Var, France

Field-hunting tip

Where it forms: A secondary mineral in the oxidized portions of a polymetallic sulfide deposit. If you start seeing anglesite, antlerite, cobaltoan-nickeloan ktenasite in float, you are in the right ground. Typical habit: platy, spherical, thin. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify thérèsemagnanite?+

Mohs hardness is 1.5-2. Luster: pearly. The streak is pale pink. Common colors include pink, light pink.

Where is thérèsemagnanite found?+

Notable localities include Cap Garonne mine, near le Pradet, Var, France.

Is thérèsemagnanite safe to handle?+

Thérèsemagnanite contains cobalt. Wash your hands afterwards, never grind or breathe the dust, and store it apart from specimens you handle often.

What rocks look like thérèsemagnanite?+

Thérèsemagnanite is most often confused with Woodwardite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with thérèsemagnanite?+

Thérèsemagnanite commonly co-occurs with Anglesite, Antlerite, Cobaltoan-nickeloan ktenasite, Cerussite, Brochantite, Covellite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does thérèsemagnanite form in?+

Where it forms: A secondary mineral in the oxidized portions of a polymetallic sulfide deposit. Working float back to the host body is the standard way to chase a fresh occurrence.

What is thérèsemagnanite used for?+

Thérèsemagnanite is used in collector.

Find thérèsemagnanite on the map

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