GUILLEMINITE

    Class : Oxides and hydroxides
    Subclass : Uranyl selenites
    Crystal system : Orthorhombic
    Chemistry : Ba(UO2)3(SeO3)2O2 3H2O
    Rarity : Very rare

The appearance of guilleminite and other uranium selenites requires the joint presence of sufficient quantities of selenium and uranium in the same deposit. These conditions are only exceptionally met, which explains the great rarity of these minerals, only 4 in number (guilleminite, demesmaekerite, derriksite, marthozite), and their presence in rare deposits. It was named in honor of Claude Guillemin, mineralogist and co-founder of the BRGM and the IMA. Guilleminite forms tabular crystals of rectangular habit not exceeding 0.4 mm in geodic voids, as well as coatings and small fibrous clusters reaching 1 cm in diameter. Its color is canary yellow.

Main photo : Guilleminite du Liauzun, Olloix, Puy-de-Dôme, France © Thierry Lesenechal

Guilleminite and malachite from Musonoï, Kolwezi, D.R. Congo © Uwe Haubenreisser
Guilleminite and malachite from Musonoï, Kolwezi, D. R. Congo © Chuck Adan
Guilleminite & vandenbrandeite from Musonoï, Kolwezi, R. D. Congo © Stephan Wolfsried
Guilleminite & vandenbrandeite from Musonoï, Kolwezi, R. D. Congo © Elmar Lackner

Guilleminite in the World

Guilleminite appears in the oxidation zone of the Musonoi deposit. Uranium comes from the oxidation of pitchblende, selenium from the alteration of a seleniferous digenite. This digenite then appears covered with microcrystalline coatings of guilleminite, derriksite and demesmaekerite.

Guilleminite in France

In France, guilleminite is reported in Liauzun, near Olloix (Puy-de-Dôme).

Twinning

No twin known for this mineral species.

Fakes and treatments

No fakes recorded for this mineral species.


Hardness : 2
Density : 4.88
Fracture : Undetermined
Streak : Light yellow

TP : Translucent
RI : 1.720 to 1.805
Birefringence : 0.085
Optical character : Biaxial -
Pleochroism : Strong
Fluorescence : None

Solubility : -

Magnetism : NoneRadioactivity : Very strong

ReCaptcha

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: https://policies.google.com/privacy

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.

Facebook

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: https://www.facebook.com/policy/cookies/

YouTube

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

Twitter

Integrated tweets and share services of Twitter are used on our website. By accepting and using these you agree to Twitter's privacy policy: https://help.twitter.com/en/rules-and-policies/twitter-cookies

PInterest

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