Muséum national d'histoire naturelle _ The species

FROM : Malachetta, Minas Gerais, Brazil
SIZE : 5 x 3.2 cm

This sample shows a yellow-green autunite crystal, fairly bright sitting on a black crystal of schorlite. This autunite crystal is squared and measures 2 x 2 x 1 cm. The dimensions of the whole sample are 5 x 3.2 cm.

Found in Malachetta, Minas Gerais, Brazil, this specimen could be acquired thanks to support from Total. This sample is currently exposed in the Room of the Treasure, within the Gallery of Mineralogy of the Muséum national d’Histoire naturelle.

Photography: Louis-Dominique Bayle, © MNHN.

SPECIE : Autunite

HISTORY : Named to recall its type-locality: Autun , Morvan area, France

Species first described in 1852 by Henry James Brooke (1771-1857) and William Hallowes Miller (1801-1880), English mineralogists

Type-locality: Saint Symphorien de Marmagne, Saône et Loire, France
ANCIENT NAME : Urane oxydé, uranite

CHEMICAL FORMULA : Ca (UO2)2 (PO4)2 10 12H2O
CRYSTAL SYSTEM : Tetragonal
COLOR : Lemon yellow to sulfur-like yellow, yellow greenish to green
DIAPHANIETY : Transparent to translucent
LUSTER : Vitreous
STREAK : Light yellow
MORPHOLOGY : Fine crystals, tabular. As aggregates
HARDNESS : 2,0-2,5
DENSITY : 3,14

CHEMICAL CLASS : VII - Phosphates, arsenat
GROUP : Autunite
STRUNZ CLASS BEFORE 2001 : 7/E.01-90
STRUNZ CLASS AFTER 2001 : 8.EB.10

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Autunite

MNHN N°193.13

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