URANOPILITE

    Class : Sulfates, chromates, molybdates
    Subclass : Hydrated sulfates
    Crystal system : Monoclinic
    Chemistry : (UO2)6(SO4)(OH)10 12H2O
    Rarity : Uncommon to fairly common

Uranopilite is a hydrated uranyl sulfate that is easily soluble and therefore of ephemeral existence. It is a neoformation mineral well known in uranium mine dumps and galleries, where it crystallizes (often on timbering) by the action of sulfuric acid formed from iron sulfides on uraninite. Exposed to UV, uranopilite is highly fluorescent in a bright yellow-green color. Its name comes from its chemical composition and from the Greek pilos (felt) in reference to its appearance. Uranopilite typically occurs as bright yellow velvety coatings or encrustations of extremely fine acicular crystals on or in close proximity to uraninite. Industrial ore leaching processes (selective dissolution of certain metals by acids) recover uranium carried in acid solutions by induced crystallization of uranopilite.


Main photo : Uranopyrite from Pribram, Czech Republic © Bohuslav Bures

Uranopilite from Shinkolobwe, DR Congo © Greg Peterson
Uranopilite from Krunkelbach Valley, Germany © Stephan Wolfsried
Uranopilite from Les Bois Noirs, St-Priest-la-Prugne, Loire, France © Pascal Chollet
Uranopilite from Lachaux, Puy-de-Dôme, France © Yannick Vessely

Uranopilite in the World

Very beautiful samples of uranopilite have been discovered in mines uranium from Katanga (Shinkolobwe, Kaolgwe), and in Jachymov (Czech Republic). It is also widespread in Canadian mines and in the Moab district (Utah).

Uranopilite in France

In France, uranopilite has been collected in fine specimens in the mines of the Massif Central, notably in Lachaux (Puy-de-Dôme) and St-Priest-la-Prugne (Loire), in La Faye near Grury (Saône-et-Loire), as well as in the small mine of Pen-ar-Ran (Loire-Atlantique). It is also known in Margnac (Haute-Vienne) and Rabejac (Hérault).

Twinning

No twinning known for this mineral species.

Fakes and treatments

No fakes listed for this mineral species.


Hardness : Undetermined
Density : 3.7 to 4
Fracture : Undetermined
Streak : Undetermined

TP : Translucent
RI : 1.621 to 1.634
Birefringence : 0.011
Optical character : Biaxial +
Pleochroism : Visible
Fluorescence : Yellow-green

Solubility : Nitric acid, hydrochloric acid, water

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/