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Opal

Hyalite

MNHN N°72.21

visu_217 infos
FROM : Valec, Boheme, Czechoslovakia
SIZE : 9.5 x 6.5 x 6 cm

general description

This sample is a hyalite (opale variety with a vitreous appearance) on a matrix of basalt. The hyalite is colourless and transparent with an icy aspect. Its shape is a globular concretions that reminds boiling water.

The sample measures 9.5 x 6.5 x 6 cm. It has been acquired in 1872, bought for 8 francs in Mr Pisani, and merchant and collector.

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.
The Species page
Identity card
SPECIE : Opal
VARIETY :Hyalite

HISTORY : Name derived from the Sanscrit "upala" meaning a precious stone; name giving later "opalus" in Latin

CHEMICAL FORMULA : SiO2 nH2O
CRYSTAL SYSTEM : Amorphe
COLOR : White, blue, yellow, violet, red, black, irisations
DIAPHANIETY : Transparent to opaque
LUSTER : Vitreous to pearly
STREAK : White
MORPHOLOGY : Amorphe
HARDNESS : 5,5-6,0
DENSITY : 1,99-2,25

CHEMICAL CLASS : IV - Oxides, hydroxides
GROUP : Moganite - opale series
STRUNZ CLASS BEFORE 2001 : 4/D.01-80
STRUNZ CLASS AFTER 2001 : 4.DA.10
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