nazwa przezroczystej, niebieskiej w odcieniach odmiany
Nieprawidłowo nazywany "szafirem Meru" – pierwsi jego odkrywcy
mylnie uznali go za
Nazwa pochodzi od
gdzie minerał ten został odkryty a została wprowadzona przez firmę
został wprowadzony dopiero w 1967 r. przez hinduskiego poszukiwacza
drogich kamieni Manuela de Souza. Kamień stał się znany przede
wszystkim dzięki biżuterii noszonej przez
– aktorkę filmową
Ca 2Al3[O|OH|SiO 4|Si2
O7] – krzemian glinu i wapnia
niebieska w odcieniach, czasami żółta, brunatna, bezbarwna
bardzo silny niebieski zielony; trichroizm widoczny już gołym okiem.
Tworzy kryształy o
słupkowym z wyraźnym pionowym prążkowaniem. Jego barwę można
wzmocnić przez ogrzewanie do temp. 400-500°C. Zawiera domieszki
Jest kruchy, niektóre okazy po oszlifowaniu wykazują
efekt kociego oka.
Istnieje możliwość pomylenia z
Znane są też imitacje tanzanitu.
Spotykany w żyłach pegmatytowo-hydrotermalnych w
– Gerevi Hills (rejon Arusha i Moshi).
Tanzanite is a very special and unique gemstone. World-wide it
occurs only in one specific location. Its blue colour which shimmers
in a slightly purplish hue is magnificent indeed. Because of its
unusually attractive flair it was easy for New York Jeweller
Tiffany's to make it one of the most sought-after and popular
gemstones in the world.
Its name reminds of the world-wide unique occurrence in the
east-African state of Tanzania. Africa – the name of this continent
does not immediately remind us of gemstones. Nevertheless, Africa is
a continent from where many splendid and beautiful stones find their
way to the world markets. An example for this is Tanzanite, which
was enthusiastically celebrated after its discovery in 1967 as "Gemstone
of the 20th Century” The gemstone experts literally held their
breaths when they were shown the first deep blue crystals mined in
the Merelani Hills near Arusha in the north of Tanzania. Millions of
years ago, metamorphous slates, gneiss stone and quarzites shaped
impressive flat insular mountains on the wide planes near Mount
Kilimanjaro. In the core of these unusual rises there are stored the
valuable crystals. For a long time they remained hidden for the eyes
of men, until one day some Massai-herdsmen passing by noticed
crystals sparkling in the sun and picked them up.
Today at Merelani the popular crystals are searched for in several,
usually smaller mines, to some extent by means of modern methods.
Generally only smaller grains are being found, but now and then the
miners strike a lucky vein and produce a larger crystal – much to
the pleasure of the mine-owners and the numerous Tanzanite
enthusiasts everywhere in the world.
The Tanzanite trade is managed by many, usually small-scale licensed
traders who have built up good business relationships with gemstone
firms in Germany, India, Israel and the USA. An estimated 90 per
cent of all Tanzanite traders are registered members of the
International Colored Stone Association ICA and thus dedicated to
the respective high ethical standards of ICA. In this way, then this
exclusive gemstone is not brought to the world markets via
suspicious back-street dealers, but in spite of its rarity is
distributed via reliable and trustworthy official channels to
well-reputed gemstone-cutters, and then passed on to the most
important jewellers all over the world.
Actually only a blue Zoisite ...
Tanzanite is in fact the blue variety of Zoisite gemstone. However,
the hydrated calcium aluminium silicate mineral achieves only
hardness 6.5 to 7 on the Moh's scale, and is thus not very resistant.
Therefore it should be worn with care, never be cleaned by
ultrasonic method and never come into contact with acids.
When New York Jeweller Company Tiffany was presented with the first
Tanzanites right after they had been discovered, they were
immediately convinced: this gemstone is a sensation! However, they
recommended finding a new name for the blue beauty, since the
gemmologically correct denomination "blue Zoisite" reminded
unfortunately of the word "suicide". So Tiffany's suggested the name
Tanzanite instead, derived from the place of occurrence, and the new
name quickly became established on the market. And it was in fact
the firm of Tiffany's who introduced the stone to the public in a
spectacular promotional campaign two years after it had been
... but what a spectacular colour!
Spectacular and magnificent is the deep blue of Tanzanite, ranging
from ultramarine to a light purplish blue. The most coveted colour
is a blue which shows a purplish hue shimmering around it, which is
extremely spectacular in sizes above ten carats. Typical for
Tanzanite is the appearance of several colours in one and the same
stone: depending on the perspective, the stone appears blue, purple,
or dun yellow. Most rough crystals, however, show a disturbingly
large proportion of brownish-yellow, but the cutter may cure this by
carefully heating the stone in an oven to about 500°C. In the course
of this heating , utmost concentration is demanded, for it is
essential to determine the moment when the colour turns blue.
Heating is therefore a treatment which is generally accepted in the
trade, however, the rough stone has to be as free of inclusions as
possible, as otherwise the process will lead to fissures in the
Working with Tanzanites is a task which will cause even experienced
cutters to tread carefully, as the cleavage of the gemstone is very
high in one direction. The exclusive stone is cut in any imaginable
shapes and forms, from classical round cuts to imaginative designer
Tanzanite is always fascinating because of its unusual appeal that
will hold everybody in its thrall. The deep blue with the slight
purple shade is one of the most extravagant colours available. It
symbolises immaculate but unusual elegance. Whoever purchases such a
unique gemstone wants to be set apart from the masses. Wearing it
communicates self-confidence and individuality. The almost magical
colour of a perfectly cut Tanzanite is not only attractive on young
women, it also emphasises the individuality of a mature woman.
For Tanzanites in especially good qualities and larger sizes almost
any price will be paid by now. What is it that makes this stone so
coveted? Is it only the spectacular colour? Well, it seems we must
also take the exclusive origin into account here. As the stone is
found on one special location only in all the world, it is
especially valuable. After all, the desire to own something unique
and rare has always been a decisive criterion for assessing the
value of special gemstones.