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What is Zoisite


#1

Hi everyone, I’ve just been offered some stones, and included are
some small parcels labelled Zoisite. I am not familiar with this
stone - they look like tanzanite to me- and in fact the word “
tanzanite” has been pencilled on to one of the parcels. Can anyone
tell me about Zoisite so I know a bit more about what I might be
dealing with, thankyou, Christine


#2

From Ganoksin Library:

Tanzanite - Zoisite - a Sorosilicate

"Tanzanite! Baron Sigismund Zois von Edelstein of Slovenia could
never have imagined that a variety of the mineral he discovered in
1805 in the Sau-Alp Mountains would cause tremendous excitement in
the jewelry industry more than a century later. The name zoisite has…

Complete story:


#3

Hi Christine, If the parcels are labeled Zoisite and the hues are
lavender (purplish blue, bluish purple), what you have is Tanzanite.
Good Pickings!

Erik


#4

Tanzanite is zoisite. Tanzanite is the trade name, zoisite the
scientific name.

Daniel R. Spirer, G.G.
Spirer Somes Jewelers
1794 Massachusetts Ave.
Cambridge, MA 02140
617-491-6000
www.spirersomes.com
@spirersomes


#5

well, if it looks like tanzanite, it probably isnt zoisite. Zoisite is the matrix around rubies. it is a deep variegated green stone with occasional red ruby inclusions. Its very pretty and very hard
Sparrow


#6

Duh Try looking at the mineral terms for tanzanite! It is indeed
zoisite that has been color changed by natural volcanic heating of
the host rock resulting in some of the most pure color available.
man can never repeat this process in the same manner so there ya
be!.

Ringman John


#7
Tanzanite is zoisite.  Tanzanite is the trade name, zoisite the
scientific name. 

Well that’s true but it’s also misleading. Tanzanite is zoisite,
yes; but the converse is not true. Tanzanite is the
blue/lavender/purple variety of zoisite and probably 99% of it has
been heat treated to achieve that color range. The bluer
manifestations of tanzanite used to be considered sapphire simulants,
but tanzanite is now so rare, expensive and beautiful in and of
itself that it has achieved a status equal or nearly equal to the
big three (sapphire, ruby, emerald).

You would certainly not call massive zoisite the opaque green
material often intermixed with ruby tanzanite. On the other hand, I
believe there’s now an attempt to market transparent, gem quality
green zoisite as “green tanzanite.” To me, that’s as bad as calling
red beryl “red emerald.”

Beth


#8

Zoisite is Basic Calcium Aluminum Silicate – in the Epidote Group!
Zoisite is Thulite and or Tanzanite! The Pink variety of Thulite is
found in Norway and the Blue variety is found in Tanzania and called
Tanzanite. Colors found are Grey, Yellow Brown, Greenish (matrix
around Rubies), Pink (Thulite), Blue (Tanzanite), vitreous. Hardness
is 6 - 6 1/2. Pink tourmaline is commonly mistaken for Thulite but
doesn’t flouresce!


#9
Duh Try looking at the mineral terms for tanzanite! It is indeed
zoisite that has been color changed by natural volcanic heating of
the host rock resulting in some of the most pure color available.
man can never repeat this process in the same manner so there ya
be!. 

Ringman, most of the tanzanite on the market (all of it, for all I
know, but i don’t know for certain) is heat treated after it’s been
mined, by the miners or cutters or someone like that, rather than
volcanic action, though certainly that could do it too. Most of
what’s mined comes out of the ground some shade of brownish color.
The stone is trichroic, showing a reddish hue in one direction, blue
in another, and strong yellow in the third. Heat treating takes out
that yellow componant, leaving just the blue and red, which interact
to give us the color range we associate with tanzanite.

Peter


#10

ok, you guys got me all confused now…

…what I have been sold (for more than 5 or 6 years) and always
shown and admired as Zoisite is a green/black semi opaque stone with
occasional ruby inclusions, since its supposed to be ruby matrix stone. and no, its NOT bloodstone, totally different stone and, in
larger pieces it`s quite obvious, that the embedded 5 cornered red
stone is natural ruby.

are you saying, that that stone is turned into violet-bluish
translucent stone? (tanzanite)

or is there another Zoisite out there maybe with a different
spelling?

clueless, in Oregon…


#11

Hi Dagmar,

are you saying, that that stone is turned into violet-bluish
translucent stone? (tanzanite) 

Not quite :-). Yes it’s the same zoisite on the chemical level; but
there are different varieties of zoisite and not all are suitable for
heat treating. The type of zoisite you’ve described (opaque and
massive with ruby inclusions) wouldn’t work. But there are
translucent to transparent varieties of brownish zoisite which are
gemmy enough to be worth turning into tanzanite by heat treating.

Think about all the varieties of quartz (both crystalline and
cryptocrystalline): rock crystal, smoky or rose quartz, amethyst,
chrysoprase, agate, jasper, etc., etc. Quartz occurs in numerous
colors and patterns as well as degrees of opacity/transparency: But
it’s all basically silicon dioxide regardless. Hope this helps.

Beth


#12

Dagmar, The Zoisite that you are describing is referred to in Walter
Schumann’s “Gemstones of the World” as Zoisite-amphibolite with ruby.

Joel Schwalb
@Joel_Schwalb
www.schwalbstudio.com