Muséum national d'histoire naturelle _ The species

FROM : Virgem de Lapa, Minas Gerais, Brazil
SIZE : 5 x 9.5 x 5.3 cm

This blue coloured topaz measures 5 x 9.5 x 5.3 cm. It comes from Virgem da Lapa in Brazil. The colour was obtained by a natural radiation unlike most of blue topaz in jewelry.The blue colour of these topaz in jewelry is obtained by an artificial radiation of the stones which are at first colourless.

This specimen was acquired by the professor Henri-Jean Schubnelthanks to support from "la maison de haute orfèvrerie Christofle".

It is today 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 : Topaz

HISTORY : Name inspired by the Greek word "τοπαζιον" [topazion] meaning "searching". This name was given to the yellow cristals found on the Topasos (Zabargat) island in the Red Sea

Species described by Anselmus Boaetius de Boodt (1150-1632), Belgian naturalist

Type-locality: undefined because species already known by the Ancients
ANCIENT NAME : Alumine fluatée siliceuse

CHEMICAL FORMULA : Al2 SiO4 (F,OH)2
CRYSTAL SYSTEM : Orthorhombic
COLOR : Colourless, yellow, pink, orange, blue
DIAPHANIETY : Transparent to opaque
LUSTER : Vitreous
STREAK : White
MORPHOLOGY : Well-formed crystals, prismatic
HARDNESS : 8
DENSITY : 3,5-3,6

CHEMICAL CLASS : VIII - Silicates
GROUP : Topaz
STRUNZ CLASS BEFORE 2001 : 8/B.02-70
STRUNZ CLASS AFTER 2001 : 9.AF.20

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Topaz

MNHN N°190.23

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