CRICHTONITE

    Class : Oxides and hydroxides
    Subclass : Oxides
    Crystal system : Trigonal
    Chemistry : (Sr,La,Ce,Y)(Ti,Fe,Mn)21O38
    Rarity : Rare

Crichtonite is a rare mineral, long confused with ilmenite. It is a mineral typical of Alpine clefts. Its name was given to it in honor of the Scottish physicist Alexander A. Crichton, also a mineral collector. It is a gray-black mineral, forming flattened lamellae, more rarely acute rhombohedra or octahedra, with a strong luster. Its appearance is reminiscent of hematite.

Main photo : Crichtonite from Pizzo Cervandone, Piedmont, Italy © Chinellato Matteo

Crichtonite from the Lauzière Massif, Savoie, France © Pascale & Daniel Journet
Crichtonite from St-Jean-de-Maurienne, Savoie, France © Pascale & Daniel Journet
Crichtonite from the Lauzière Massif, Savoie, France © Enrico Bonacina
Twinned crichtonite from Presidente Kubitschek, Minas Gerais, Brazil © Jolyon Ralph

Crichtonite in the World

The best known crichtonite crystals are 25 mm sharp rhombohedra and come from Val Tavetsch in the Swiss Graubünden. Good centimeter crystals were also provided by the clefts of Pizzo Cervandone (Italy).

Crichtonite in France

In France, crichtonite is known in centimeter-sized crystals in the Alpine clefts of Bourg d'Oisans (Isère), its type locality, as well as in the Lauzière Massif (Savoie).

Twinning

A multiple twin is known and produces pseudohexagonal crystals up to 2 cm in particular on the Presidente Kubitschek deposit (Minas Gerais, Brazil).

Fakes and treatments

No fakes listed for this mineral species, but easy to confuse with hematite without chemical analysis...


Hardness : 5 to 6
Density : 4.46
Fracture : Conchoidal
Streak : Grey

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

Solubility : Insoluble


Magnetism : None
Radioactivity : None