Sturmanite - Encyclopedia

    Class : Sulphates, chromates, molybdates
    Subclass : Hydrated sulphates
    Crystal system : Rhombohedral
    Chemistry : Ca6Fe2(SO4)2[B(OH)4](OH)12 25H2O
    Rarity : Very rare


Sturmanite is an hydrated sulfate of the ettringite group, which forms prismatic hexagonal bipyramidal crystals of yellow to yellow-green color, rarely brown. It owes its name to B. Darko Sturman, Assistant Curator of the Royal Ontario Museum in Toronto, Canada. It is found in the oxidation zone of a manganese deposit. It is a mineral with a complex structure, [B(OH)4] groups partially substituting for SO4 groups. It is a very rare mineral sought after by the most informed collectors.

Sturmanite in the World

Sturmanite is found exclusively in the manganese mines of the Hotazel district in South Africa : exceptional crystals exceeding 30 cm come from the N'Chwaning II mine, those of Black Rock and Wessel having provided superb crystals, but of more modest dimensions (4 cm at most).

Sturmanite in France

This mineral is not present in the French underground.

Twinning

Twinning probable but not described.

Fakes and scams

No fake recorded for this species. It is a very difficult mineral to differentiate from ettringite without chemical analysis, some specimens of ettringite may be labeled sturmanite and vice versa. Some crystals may exhibit mixtures and be zoned with parts of ettringite composition and other sturmanite.



Hardness : 2.5
Density : 1,847
Fracture : Undeterminated
Streak : Brown to yellow




TP : Transparent to translucent
IR : 1.499 to 1.505
Birefringence : 0.002
Optical character : Uniaxial (+/-)
Pleochroism : Low
Fluorescence : None


Solubility : Insoluble

Magnetism : None
Radioactivity : None

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/