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Mambertiite is an extremely rare bismuth-chromium sulfate-chromate mineral discovered at the La Filona mine in France. It typically occurs as small, pale yellow transparent tabular crystals associated with other secondary bismuth minerals. Due to its discovery in a specific mine site, it is highly sought after by advanced mineral collectors specializing in rare species.

Hardness
2
Mohs
Luster
Vitreous
Streak
White
Transparency
Transparent

Is this mambertiite?

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 mambertiite with a known reference. Mambertiite sits at Mohs 2 — softer than the next harder reference, harder than the previous one.
  • 2
    Check the streak
    Drag the specimen across an unglazed porcelain plate. Mambertiite leaves a white streak.
  • 3
    Read the luster
    Hold the specimen under a strong light. Mambertiite typically shows a vitreous luster.
  • 4
    Match the color range
    Compare against the expected color range: yellow, pale yellow.
  • 5
    Look at form & habit
    Crystal system: triclinic. Typical habit: tabular crystals.

Often confused with

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

Bismutite mineral
mineral
Bismutite
Mohs 3

How to tell apart: Bismutite is the harder of the two (Mohs 3 vs. 2); luster reads vitreous on Mambertiite and pearly on Bismutite.

Compare →

Often found alongside mambertiite

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

All properties

Chemical formula
Bi₄O₂(OH)₂(CrO₄)(SO₄)
Mohs hardness
2
Density
4.15 g/cm³
Colors
YellowPale Yellow
Streak
White
Luster
Vitreous
Transparency
Transparent
Crystal system
Triclinic
Crystal habit
Tabular Crystals
Cleavage
Perfect
Rarity
Rare
Uses
Collector
Host rock
Hydrothermal Veins
Typical price
$100-500 thumbnail

Where rockhounds find mambertiite

Classic worldwide localities

  • La Filona mine, Hérault, France

Field-hunting tip

Look in hydrothermal veins country — that is the host setting where mambertiite typically forms. If you start seeing bismutite, quartz in float, you are in the right ground. Field specimens usually show a tabular crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify mambertiite?+
Mohs hardness is 2. It typically shows a vitreous luster. The streak is white. Common colors include yellow, pale yellow.
Where is mambertiite found?+
Notable localities include La Filona mine, Hérault, France.
How much is mambertiite worth?+
Typical asking prices fall in the range of $100-500 thumbnail. Quality, size, and provenance can move individual specimens well outside that range.
Is mambertiite safe to handle?+
It contains toxic constituents. Contains bismuth and chromium; wash hands thoroughly after handling and avoid inhaling dust. Handle with care, avoid grinding or breathing dust, and store separately.
What rocks look like mambertiite?+
Mambertiite is most often confused with Bismutite. A quick hardness test and a streak check separate the look-alikes faster than color alone.
What minerals are found with mambertiite?+
Mambertiite commonly co-occurs with Bismutite, Quartz. Spotting any of these in float or country rock is a useful trip signal.
What kind of rock does mambertiite form in?+
Mambertiite typically forms in hydrothermal veins. Working float back to the host body is the standard way to chase a fresh occurrence.
What is mambertiite used for?+
Mambertiite is used in collector.

Find mambertiite on the map

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

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