Crichtonite , Quartz Locality: St Christophe-en-Oisans, Bourg d'Oisans , Isère , Rhône-Alpes , France ( Locality at mindat.org ) Crichtonite is a very rare, complex oxide containing a number of rare earths. This is surely an old piece, as it comes from the now defunct old workings of the TYPE LOCALITY in Isere. This piece features sharp crystals of up to 2 mm, on contrasting matrix, and they are readily visible. 6 x 4.6 x 3.2 cm. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Crichtonite
Crichtonite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula Sr(Mn,Y,U)Fe₂(Ti,Fe,Cr,V)₁₈(O,OH)₃₈.
It crystallizes in the trigonal crystal system (space group R-3). It is a member of the Crichtonite structural group.
Key properties: Mohs hardness 4.5–5; specific gravity 4.46; Metallic, dull to bright luster.
IMA symbol Cic, IMA status: approved, named in 1814.
Found in alpine-type fissure veins.
It is found associated with Quartz, chlorite.
The name refers to Sir Alexander A. Crichton (1763–1856), Scottish physician and mineral collector, once physician to the Russian Czar Alexander I.