Muséum national d'histoire naturelle _ The species

FROM : Lavra Navegadura, Minas Gerais, Brazil
SIZE : 20 x 13 cm

This sample is made of white albite (cleavelandite variety) on which some hexgonal silvery gray layers of muscovite are spread. Lamellar crystals of cleavelandite are well-formed , they measure up to 6 cm in length and 0.5 in width. The whole measures 20 x 13 cm.

This specimen comes from Lavra Navegadura in Brazil. The Muséum national d’Histoire naturelle could obtain this specimen thanks to the support from Total. It is kept in the storage rooms of the collections of the (i.e., not yet displayed to the public).

Photography: Louis-Dominique Bayle, © MNHN.

SPECIE : Albite
VARIETY :Cleavelandite

HISTORY : Name derived from Latin "albus" meaning white, Name given for its color

Species first described in 1815 by Johan Gottlied Gahn (1745-1818) and Jöns Jacob Berzélius (1179-1848), Swedish chemists

Type-locality: Finnbo, Kopparberg, Suède

CHEMICAL FORMULA : Na Al Si3 O8
CRYSTAL SYSTEM : Triclinic
COLOR : White to gray, greenish, blueish
DIAPHANIETY : Transparent to translucide
LUSTER : Vitreous to pearly
STREAK : White
MORPHOLOGY : Crystals often tabular
HARDNESS : 6,0-6,5
DENSITY : 2,609-2,621

CHEMICAL CLASS : VIII - Silicates
GROUP : Feldspath plagioclase
STRUNZ CLASS BEFORE 2001 : 8/J.07-20
STRUNZ CLASS AFTER 2001 : 9.FA.25

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Albite

Cleavelandite

MNHN N°204.173

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