Johannsenite - Encyclopedia

Johannsénite et sphalérite de Iron Cap Mine, Arizona, USA © Lawrence Violett

    Class : Silicates
    Subclass : Inosilicates
    Crystal system : Monoclinic
    Chemistry : CaMnSi2O6
    Rarity : Quite common

Johannsenite is a manganese clinopyroxene which forms two series, with diopside on the one hand and with hedenbergite on the other. It is found in limestones which have undergone contact metamorphism with metasomatosis and which are therefore transformed into skarns. It accompanies other manganese silicates (bustamite, rhodonite) and frequent sulphides. It was named in honor of Albert Johannsen, American petrographer and geologist, Professor at the University of Chicago. Johannsenite forms fibrous crystals which are usually grouped into fibroradiated spherolites or radiated aggregates ; they can reach 10 cm. Their green-black or brown color is often blackened by a film of manganese oxides. Johannsenite also alters to rhodonite. It is a locally important manganese ore and it is occasionnally cut in cabochons.

Main photo : Johannsenite and sphalerite from Iron Cap Mine, Arizona, USA © Lawrence Violett

Johannsenite from Iron Cap Mine, Arizona, USA © Oliver Dziallas
Johannsenite from Wessels Mine, South Africa © Bruce Cairncross
Johannsenite altered in rhodonite from Civillina, Italy © Giovanni Golinelli
Johannsenite from Civillina Mountain, Italy © Enrico Bonacina

Johannesite in the World

The best samples come from Broken Hill (Australia) where centimeter-sized groups of bronze-green crystals were discovered. The famous Franklin deposit (New Jersey) also produced beautiful crystallizations, as did several other American deposits like Iron Cap (Arizona). In Teragoshi (Japan), johannsenite was the main manganese ore.

Johannesite in France

In France, johannsenite is reported from the Costabonne mines (Pyrénées-Orientales).


No twins known for this mineral species.

Fakes and treatments

No fakes recorded for this mineral species.

Hardness : 6
Density : 3.56
Fracture : Irregular
Streak : White

TP : Translucent
RI : 1.703 to 1.745
Birefringence : 0.029
Optical character : Biaxial +
Pleochroism : Low
Fluorescence : None

Solubility : Hydrochloric acid

Magnetism : NoneRadioactivity : 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: