RAMSDELLITE

    Class : Oxides and hydroxides
    Subclass : Oxides
    Crystal system : Orthorhombic
    Chemistry : MnO2
    Rarity : Uncommon

Ramsdellite is a fairly rare manganese oxide. It is a secondary mineral of deposits containing manganese, which is formed by transformation of one of its polymorphs, pyrolusite (the other being akhtenskite), or groutite. It was named in honor of Lewis Stephen Ramsdell, Professor of Mineralogy at the University of Michigan. Ramsdellite occurs mainly in crusts, in fibrous or lamellar masses, or in steel gray to black crystals which are usually groutite pseudomorph. It is a very accessory ore of manganese.

Main photo : Ramsdellite from Lake Valley, New Mexico, USA © Ronnie Van Dommelen

Ramsdellite from Mistake Mine, Arizona, USA © Chris Emproto
Ramsdellite from Priceless Mine, Arizona, USA © Michael C. Roarke
Ramsdellite from Mount Corno Quarry, Lusiana, Italy © Antonio Zordan
Ramsdellite from Rivet, Peyrebrune, Tarn, France © Thierry Brunsperger

Ramsdellite in the World

The most beautiful known specimens of ramsdellite are 1 cm crystals from the German deposit of Bütten-Adenstedt (Lower Saxony), the Mistake manganese mine near Wickenburg (Arizona) and Lake Valley (New Mexico). This mineral is relatively common in deposits in the Hotazel region (South Africa) and in the oxidation zone of manganese veins in Germany (Clara mine, Black Forest), Bohemia (Horni Blatna) and Mexico (Los Gavilanes), among others. Ramsdellite is also known from quite a few other localities, notably in the oxidation zone of the large iron-manganese deposit of Iron Monarch, in Australia, and in several American deposits, for example the rhodochrosite - rhodonite veins of Butte (Montana).

Ramsdellite in France

In France, ramsdellite is known in Saphoz (Haute-Saône), in Ste-Marie-aux-Mines (Haut-Rhin), in Montebras (Creuse), in the Aure valley (Haute-Pyrénées) and in Peyrebrune (Tarn).

Twinning

No twins known for this mineral species.

Fakes and treatments

No fakes listed for this mineral species.


Hardness : 3
Density : 4.37
Fracture : Undetermined
Streak : Brown-black

TP : Opaque
RI : -
Birefringence : -
Optical character : -
Pleochroism : None
Fluorescence : None

Solubility : -

Magnetism : NoneRadioactivity : None