Muséum national d'histoire naturelle _ The species

FROM : Arusha, Tanzania
SIZE : 3.7 x 2.5 x 2 cm

This crystal is tanzanite (blue zoisite variety). Its color is spectacular, it is indigo-blue-tinted. It shows a pronounced pleochroism from marine blue to purple-red or purple-blue red determined upon the angle of view. This sample measures 3.7 x 2.5 x 2 cm.

This crystal comes from Merelani deposit in Arusha area in Tanzania. It has been acquired thanks to support from Total. It is kept in the storage rooms of the collections of the Muséum national d’Histoire naturelle (i.e., not yet displayed to the public).

Photography: Louis-Dominique Bayle, © MNHN.

SPECIE : Zoisite
VARIETY :Tanzanite

HISTORY : Species dedicated to Earl Siegmund Zoïs (1747-1819), Austrian naturalist and mineralogist

Species first described in 1805 by Abraham Gottlob Werner (1749-1817), German geologist, Bergwerk Akademie, Freiberg, Germany

Type-locality: Saualpe, Carinthia, Austria

CHEMICAL FORMULA : Ca2 Al3 (SiO4)3 (OH)
CRYSTAL SYSTEM : Orthorhombic
COLOR : Colorless, gray, white, blue, pink, greenish
DIAPHANIETY : Transparent to translucent
LUSTER : Vitreous
STREAK : White
MORPHOLOGY : Prismatic crystals
HARDNESS : 6,7
DENSITY : 3,35

CHEMICAL CLASS : VIII - Silicates
GROUP : Zoisite
STRUNZ CLASS BEFORE 2001 : 8/C.23-100
STRUNZ CLASS AFTER 2001 : 9.BG.10

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Tanzanite

MNHN N°170.184

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