Muséum national d'histoire naturelle _ The species

FROM : Trimouns, Luzenac, Ariège, France
SIZE : 9 x 6.5 cm

This specimen shows two brown crystals of allanite (cf detail 1) associated to white dolomite. The allanite is transparent and is well crystallized. The largest crystal measures 1.5 x 0.4 cm; the whole sample measuring 9 x 6.5 cm.

This sample was discovered in the quarry of Trimouns in Ariège. The support from Total made its acquisition possible. This sample is currently exposed in the Treasure Room, within the Gallery of Mineralogy of the Muséum national d’Histoire naturelle

Photography: Louis-Dominique Bayle, © MNHN.

SPECIE : Allanite (Ce)

HISTORY : Species dedicated to Thomas Allan (1777-1833), Scottish mineralogist who discovered the mineral

Species first described in 1810 by Thomas Thomson (1773-1852), Scottish mineralogist and chemist

Type-locality: Iglorsoit, Groënland
ANCIENT NAME : Orthite

CHEMICAL FORMULA : (Ca,Ce)2 (Al,Fe2+,Fe3+)3 (SiO4) (Si2O7) O (OH)
CRYSTAL SYSTEM : Monoclinic
COLOR : Brown to black
DIAPHANIETY : Translucent to opaque
LUSTER : Vitreous to resineous
STREAK : Gray
MORPHOLOGY : Tabular crystals, prismatic to acicular
HARDNESS : 5,5-6,0
DENSITY : 4,11

CHEMICAL CLASS : IX - Silicates
GROUP : Epidote
STRUNZ CLASS BEFORE 2001 : 8/C.23-80
STRUNZ CLASS AFTER 2001 : 9.BG.05

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Allanite (Ce)

Allanite (Ce)

MNHN N°195.263

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