Best viewed using Adobe Flash Player (8 or higher).
Download hereGENERAL DESCRIPTION
Beryl is a beryllium aluminosilicate. It constitutes the principal source of beryllium. Its gemmeous varieties are also appreciated.
According to the colour of the crystals, several varieties of beryl are distinguished : emerald, green (coloured by chromium), aquamarina, light-green blue (coloured by both ferrous and ferric iron), heliodor, yellow (due to the presence of ferric iron), morganite, pink (containing divalent manganese), the bixbite, red (due to the presence of trivalent manganese).
Except morganite which has flattened crystal morphologies, beryl generally forms lengthened hexagonal crystals. Primarily of pegmatitic and pneumatolytic origins, beryl can form large-sized crystals. Only the red variety is of volcanic origins. The largest known crystal is 18 founders long and 3,5 founders in diameter. It was collected near Malakialina (Madagascar).
Although it is a rather common mineral of large pegmatites, the gem-qualityvarieties are relatively rare. Certain deposits of Siberia, Mined-Gerais (Brazil) or Muso and Chivor (Colombia) have provided gemmeous stones for several centuries. The deposits of Madagascar also produced beautiful samples.
In France, beryl is a relatively common mineral of the granitic areas. It is found for example in the Limousin (Mounts d’ Ambazac, Pont of Barost and Chanteloube in Haute-Vienne), in Auvergne (mine of Montmins, quarry of Beauvoir in Allier). In the tin deposits of Villeder (Morbihan), the beryl is common and associated to blue apatite. Also found at the mines of Framont (Vosges), the quarries of Coray (Finistere) of Pont-Péan (Orne), Orvrault and Abbaretz (Loire-Atlantique), Vendée (Les Herbiers, beach of Les Sables d’ Olonne) and in the Alps (massifs of Chamonix, Lauzière and Tarentaise). Finally, it is also present in Guyana in the Tamanoir massif.
Thanks to dissolution of a fragment of "béril de France" (beryl from Limousin, France) kept at the Muséum national d’ Histoire naturelle in Paris, N. L. Vauquelin discovered the element beryllium (Be) in 1798. This fragment is at the same time the chemical holotype chemical and the neotype of beryl.
Finally, the yellow and green beryls of the Haüy collection could be regarded as crystallographic cotypes.
HISTORY : Name inspired from the Greek word "βερυλλοσ" [beryllos] that designed precious stones having the color of sewater
Word used en 77 by Caius Plinius Secundus (30-79 AD), Roman naturalist
Type-locality: undefined because species already known from the Ancients
ANCIENT NAME : Béril
CHEMICAL FORMULA : Be3 Al2 Si6O18
CRYSTAL SYSTEM : Hexagonal
COLOR : Colourless, white, green, yellow, pink, red, blue
DIAPHANIETY : Transparent to translucent
LUSTER : Vitreous
STREAK : White
MORPHOLOGIE : Prismatic crystals, hexagonal, forming aggregates, massive
HARDNESS : 7,5-8,0
CHEMICAL CLASS: 2,64
DENSITY : VIII - Silicates
GROUP : Beryl
STRUNZ CLASS BEFORE 2001 : 8/E.12-10
STRUNZ CLASS AFTER 2001 : 9.CJ.05
