Bournonite - Encyclopedia

    Class : Sulphides and sulfosalts
    Subclass : Sulfosalts
    Crystal system : Orthorhombic
    Chemistry : PbCuSbS3
    Rarity : Quite common

Bournonite is a relatively common sulfo-antimonide in medium and low temperature hydrothermal veins. It frequently associated with galena, pyrite, sphalerite, tetrahedrite, chalcopyrite, fluorite and barite. It owes its name to the French crystallographer, Count Jacques Louis de Bournon who described the mineral. It is presented in flattened pseudo-tetragonal crystals, often implanted on the edge with striated prism faces, in short, tabular prismatic crystals with fluted faces up to 11 cm, or in compact masses sometimes grainy. The bournonite is especially famous for its characteristic cruciform twins in "cogwheel". It has an often bright metallic luster and a steel gray color tending toward black. Highly weatherable, it frequently gives rise to a procession of variously colored oxides of copper, lead and antimony. Bournonite has occasionally been used as copper, lead and sometimes antimony ore, it is no longer used today but its crystals are still appreciated by mineral collectors.

Main photo : Bournonite from St-Laurent-le-Minier, Gard, France

Bournonite from Loiras, Herault, France
Twinned bournonite from Quiruvilca Mine, Peru
Bournonite on pyrite from Trepca, Kosovo
Bournonite from Les Malines, Gard, France

Bournonite in the World

Exceptional crystals come from English Cornwall (15 cm twinned crystals) and from Harz in Germany (15 cm tabular crystals on siderite). Superb centimetric crystals were also extracted from the Bolivian mines (Vibora : 15 cm crystals) and Peruvian (Oraya : 4 cm crystals).

Bournonite in France

In France, interesting groups of crystals were found at Pontgibaud (Puy-de-Dôme : 3 cm tabular crystals), at the Barlet fluorite mine near Langeac, Haute-Loire (photo on the right), at Les Maline Mine (Gard : 6 cm crystals), but especially at the Prunières mine (La Mure, Isère) which provided the most beautiful specimens : 5 cm tabular crystals implanted on siderite and tetrahedrite. The quarry of Loiras (Hérault) has when it provided crystals up to 2 cm on white dolomite.


Very common on {110} this twin repeats to form crystals with cruciform facies called "cogwheels".


Some crystals, from Les Malines (Gard) especially, could be brushed with Dremel to improve the surface quality.

Hardness : 2.5 to 3
Density : 5.83
Fracture : Irregular to sub-conchoidal
Streak : Gray

TP : Opaque
RI : Not measurable
Birefringence : Not measurable
Optical character : None
Pleochroism : None
Fluorescence : None

Solubility : Nitric acid

Magnetism : Paramagnetic
Radioactivity : None


This service is used to secure web forms of our website and required if you want to contact us. By accepting it you agree to Google's privacy policy:

Google Analytics

Google Analytics is a service used on our website that tracks, reports traffic and measures how users interact with our website content in order for us to improve it and provide better services.


Our website allows you to like or share its content on Facebook social network. By activating and using it you agree to Facebook's privacy policy:


Integrated videos provided by YouTube are used on our website. By accepting to watch them you agree to Google's privacy policy:


Integrated tweets and share services of Twitter are used on our website. By accepting and using these you agree to Twitter's privacy policy:


Our website allows you to share its content on PInterest social network. By activating and using it you agree to PInterest's privacy policy: