Mineral description : Allanite-(Ce)

Allanite from Bastnäs.
Allanite as a vein in cerite from Bastnäs.

Mineral class Silicates : Soro silicates : Epidote - Vesuvian group
Chemical formula (Ce,Ca,Y)2Fe2Al2(O/OH/SiO4/Si2O7)
Crystal system Monoclinic
Habitus As long thin prismatic crystals. Also as grainy and massive aggregates.
Cleavage Imperfect along [001] and [100], fracture conchoidal.
Hardness 5.5
Density 3.3-4.2
Color Black to brown. Translucent to opaque.
Streak Grayish brown.
Luster Vitreous, greasy.
Notes Sometimes radioactive.
Easy to ignite.
Soluble in hydrochloric acid.
Locations A number of localities exists in Sweden.
  • Åskagen quartz quarry, Värmland. As big prisms.
  • Skillnabo quartz quarry, Västergötland. As big prisms.
  • Kårarvet and Finnbo quartz quarries, Falun. As radiating bundles.
  • Ytterby feldspar quarry, Resarö, Stockholm. As radiating crystals.
  • Slättåkra, Alsheda, Småland. Up to fist sized aggregates in a pegmatite.
  • Östra Gyttorpsgruvan, Nora. The largest locality in Sweden. Over 20 tons have been mined and aggregates of up to 100 kg have been found.
  • Bastnäs, Riddarhyttan, Västmanland. As platy individes with cerite.
If anyone knows if the allanite from the above localities are radioactive or not, send me an email so I could include it here. Thanks.

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Last changed : 1998-08-01