Muséum national d'histoire naturelle _ The species

FROM : Mont Malosa, Malawi
SIZE : Crystals: 3 cm

This sample is eudidymite and has white tabular pseudo-triangular crystals from 2 cm to 3 cm. They are associated with crystals of microcline and black acmite (aegyrine).

This sample comes from Malawi and was acquired thanks to support from Total. It is kept today 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 : Eudidymite

HISTORY : Name inspired by the Greek word "ευ" [eu] meaning good et "διδυμοσ" [didumos] meaning "twins" in reference to its frequent twinneds

Species described in 1887 by Waldemar Christopher Brøgger (1851-1940), Norvegian geologist and mineralogist

Type-locality: Aro island, Langesundfjorden, Larvik, Norway

CHEMICAL FORMULA : Na Be Si3O7 (OH)
CRYSTAL SYSTEM : Monoclinic
COLOR : Colorless to white, more scarcely blue, violet
DIAPHANIETY : Transparent to translucent
LUSTER : Vitreous
STREAK : White
MORPHOLOGY : Tabular crystals up to 5 cm, frequently twinneds, aggregates, massive
HARDNESS : 6,0
DENSITY : 2,57

CHEMICAL CLASS : VIII - Silicates
GROUP : Epididymite - eudidymite series
STRUNZ CLASS BEFORE 2001 : 8/G.04-10
STRUNZ CLASS AFTER 2001 : 9.DG.35

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Eudidymite

Eudidymite

MNHN N°204.147

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