Topaz (mineral)

The topaz , of the name of the Topasos island in the Red Sea, is a crystal of fluoro Silicate of Aluminum (Minéral). It crystallizes in the orthorhombic system and its chemical formula is: Al₂SiO₄ (F, OH) ₂.

It is used in Joaillerie and is classified like Semiprecious stone.

Topaz can be colorless, white, blue pale, yellow clearly, brown-yellow, brown rosâtre and rosy (the darker nuances are often obtained by heating or irradiation); it is heavy (Densité of 3,5-3,6), lasts (Dureté of 8) and inalterable (infusible and insoluble in the acid); its crystalline forms make it seek by the collectors.

The name of the stone comes from the island of Topazos (τοπαζος, today Zagarbad, or Zagarjad), island of the Red Sea located at broad of the peninsula of Short-nap cloth banas, where the Égyptiens, then the Romains, exploited the Olivine (called Chrysolite or Péridot by the jewellers).

Indeed, since the Antiquity until the Rebirth, various gems of yellow color were called “topaz”; this use remained by associating qualitative with it:

the topaz of Spain or gilded topaz is a heated quartz;
the topaz of the India S or Eastern topaz is a yellow Saphir;
the topaz of Bohemia , or Western topaz , is a Citrine.

Layers

Topaz was particularly abundant at the 19th century close to the village of Alabaskha, in the the Ural (Russia).

Today, it is it particularly with the Brésil, in particular in the State of Minas Gerais; however, it meets in the whole world (Australia, California, Japan, etc).

The crystals can be enormous, and reach several tens of kilograms in some Brazilian Pegmatite S.

Symbolic system

The Noces of topaz symbolize the 44 years of Mariage in the French folklore.

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