Tanzanite – Harry & Co Jewellery

General Information about Tanzanite

Tanzanite is a variety of the mineral zoisite.
It is a sorosilicate with the chemical formula (Ca(SiO)(Si)O(OH)) + (Cr,Sr).
Tanzanite belongs to the epidote mineral group.
It is known for its royal blue, indigo, and violet/purple color.
The crystal habit of tanzanite is prismatic with striations; it can also be massive to columnar.

Tanzanite was formed around 585 million years ago during the mid-Ediacaran Period.
It was formed due to plate tectonic activity and intense heat in the area that later became Mount Kilimanjaro.
Deposits of tanzanite are typically found in the hinge of isoclinal folds.
The mineral is located in a complex geological environment.
Tanzanite was discovered in January 1967 by Jumanne Mhero Ngoma.
Ngoma found the sparkling blue stones at the Mererani hills in the Kiteto district of Tanzania.
The gemstone was initially mistaken for olivine and dumortierite before being correctly identified as a variety of zoisite.
The name 'tanzanite' was given to the gemstone by Tiffany & Co. after Tanzania, the country of its discovery.

In July 1967, transparent fragments of tanzanite were found by Manuel de Souza near Mererani.
The gemstone was initially thought to be olivine or dumortierite.
The correct identification was made by the Gemological Institute of America and other mineralogists.
Tiffany & Co. renamed the gemstone as 'tanzanite' to capitalize on its rarity and single location.
In 1971, the Tanzanian government nationalized the tanzanite mines.
The Tanzanian government split the tanzanite mines into four sections: Blocks A, B, C, and D.
TanzaniteOne, a major player in the tanzanite market, obtained the lease for Block C.
Legislation was introduced in 2003 to ban the export of unprocessed tanzanite to India.
In 2010, the government banned the export of rough stones weighing more than one gram.
TanzaniteOne Mining Ltd. is owned by Richland Resources and had a record production in 2019.

Tanzanite forms as a brownish crystal and is trichroic, showing three colors concurrently: brown, blue, and violet.
Heating removes the brown or burgundy color component, producing a stronger violet-blue color and making the stone dichroic.
Some gem-quality tanzanite can heat to a green primary hue, but it is seldom of interest to commercial buyers.
Heat treatment is usually carried out at temperatures between 370 and 390°C for 30 minutes.
Tanzanite found close to the surface in the early days of discovery may not require heat treatment.
Tanzanite is a pleochroic gemstone, meaning it appears to have multiple colors based on the angle of light.
Most tanzanite appears blue when viewed from one direction but can vary from violet to red when seen from a different angle.
The cutting process can be challenging due to the problem of selecting the perfect color.
The finished color of the gemstone depends on how the table cut reflects the light.

Tanzanite has never been successfully synthesized in a laboratory, so all genuine tanzanite is naturally occurring.
Tanzanite has been imitated using materials such as cubic zirconia, synthetic spinel, yttrium aluminium garnet, and colored glass.
Genuine tanzanite can be distinguished from imitations using a dichroscope, as only tanzanite will appear doubly refractive.
Synthetic forsterite has been sold as tanzanite but can be distinguished through refractometer readings and Hanneman filter tests.
Lower grades of tanzanite are occasionally enhanced using a layer of cobalt, but the practice is considered deceptive unless disclosed.

Reference	URL
Glossary	https://harryandcojewellery.com.au/blogs/glossary/tanzanite
Wikipedia	http://en.wikipedia.org/wiki/Tanzanite
Wikidata	https://www.wikidata.org/wiki/Q429942
Knowledge Graph	https://www.google.com/search?kgmid=/m/01stxp