( Fr- zoisite; Ger- Zoisit;
Nor- zoisitt; Rus- )
A. Zoisite-ruby rock carving
(height - 19 cm) made from Tanzania material. Betty Llewellyn
collection. (© photo by Jeffrey A. Scovil)
DESCRIPTION: Two compact, massive,
zoisite-rich rocks have found use as gemrocks: chromiferous
zoisite and manganiferous zoisite. Neither of these two rocks,
however, is the most used zoisite-rich rock for fashioing decorative
items. That role falls to the zoisite-rich rocks in which red
is surrounded by green zoisite plus or minus a dark amphibole, usually
referred to as hornblende, but in some records is reported as
www-2.cs.cmu.edu). The zoisite of these rocks is typically granular and
to appear sugary in most rough. The red corundum is typically a
low-grade ruby, which in some rocks exhibits fair to good hexagonal
crystal outlines. The black amphibole commonly is manifest as speckles
but in some rocks defines streaks that give the rock an overall
gneissic appearance. The following properties are for the
zoisite of these rocks:
Colors - apple-green (zoisite, likely
chromiferous but usually not so-designated ) or
rose-pink to purplish (thulite).
H. 6 -6½
S.G. 3.15 -3.37
Light transmission - translucent to opaque
Luster - pearly
uneven to subconchoidal
The red corundum grains in some of the ruby...zoisite rocks have corona
like shell consisting of an off-white to yellowish material that, according to Chris Wright of Wright's Rock
Shop, Hot Springs, Arkansas (personal communication, July, 2005) are
"variations in the zoisite".
USES: Anyolite has
been carved, usually to
exhibit both its red corundum and green zoisite constituents and their
interrelationships to advantage -- see above Figure; some
jewelry, usually relatively large pieces that display interrelations
between major components; also spheres, eggs, hearts, pyramids etc.; and massage
points and wands and "palm stones."
Thulite has been used chiefly for fashioning cabochons and diverse
ornaments. Both the green and pink more or less pure zoisites and
saussurite (see REMARKS)
have found use
as jade substitutes.
- Anyolite is the name frequently applied to all
gemrocks that consist largely of massive
apple-green zoisite plus ruby-red corundum (i.e., medium or relatively low
grade ruby) ±
hornblende. Ruby-zoisite, ruby in zoisite, ruby-in-zoisite and
Tanganyika artstone are alternative names given this gemrock,
especially in the market place.
- Rosaline - marketplace name sometimes given
- Ruby-zoisite and
ruby(-)in(-)zoisite, as just mentioned, are other designations used for
particularly in the marketplace. I suspect "ruby" is given
primary billing for these rocks because of its likely appeal to
potential buyers despite the fact that, considering the relative
volumes of these components in these rocks, it would seem more appropriate for zoisite to be given top billing (see Figure A).
- Tanganyika artstone - another name sometimes
given to the green zoisite-ruby ... rock from Tanzania.
- Thulite - name
usually applied to the rose-pink to purplish, zoisite. Thulite
that is massive, the common occurrence, is used as gemrock. The
term thulite is used widely in scientific
literature as the varietal name for any pink zoisite thought to be pink
because of its manganese content, as well as in marketplace flyers etc.
OCCURRENCES: Metamorphic rocks: Zoisite-rich rocks as a
group have had so many diferent origins suggested
for them that it seems hardly worth repeating most of them here.
Thulite, for example, typically as fracture
fillings and as veins
that transect several diverse, commonly metamorphic rocks, but several
other occurrences have also been recorded. Most, if not all,
quality anyolite seems to
occur as altered
Thulite -- Little Chief Mine,
Alaska and Telemark, Norway. Anyolite
Longido, northeastern Tanzania (formerly Tanganyika).
REMARKS: Zoisite was named for the
noble, Sigmund (Žiga)
Zois (1747-1819), Baron of Edelstein, whose interest
minerals led to his financing mineral collecting expeditions. It is said, however,
that this mineral, first found in 1805 on the Svinška Planina
(Sau-Alps) of Carinthia, Austria, was originally called
saualpite and only later
renamed zoisite. And, " While at first
this may seem a travesty of scientific justice,
we can at least rest assured that matters could have been worse. The
name ... 'saualpite' ...
Literally translated from the German, 'saualp' means 'female pig
mountain.'"(/www.laketahoejewelers.com) Thulite was named for Thule,
a former name for
Norway, not, as
Thule, Greenland; it was first described from Kleppan, Souland,
Telemark, Norway. The name anyolite is
apparently from the Masai (of Tanzania)
word for green. Its type locality is near Longido, Tanzania.
Ruby-zoisite rocks are difficult
fashion because of marked differences of hardness of their chief
constituents -- i.e., On the
Mohs hardness scale, zoisite and hornblende (or tschermakite) have
hardnesses about about 6½, whereas corundum has a hardness of 9. In any
case, carvers usually try to fashion these rocks to
use the colors artistically and, in most cases, to emphasize the red
corundum-rich parts of these rocks.
Mineralogically, zoisite is a member of the epidote group, the other
members of which are clinozoisite, epidote per se, piemontite, and
allanite. Thulite is the only variety of zoisite that commonly
occurs as compact masses used as such as gemrock. As already
mentioned, the so-called ruby-zoisite gemrocks include large
percentages of minerals other than zoisite. Epidote per se is a specific, though
commonly minor, constituent of
the gemrock unakite (see UNAKITE entry) and also of Bowesite, Okkolite and
the unnamed epidote-quartz rock, all of which are included in APPENDIX
A. In addition, saussurite (named for the famous Swiss naturalist, explorer and
inventor Horace Bénédict de Saussure),
which is made up largely of microscopic mixtures of zoisite and/or
epidote plus a sodium-rich
plagioclase feldspar (typically albite or albit-oligoclase), has been
used as a jade simulant under names such
as Swiss jade and Nanyang jade (see JADE entry).
Tanzanite, another variety of the mineral
zoisite has found wide acceptance as a gemstone.
however, is a
macrocrystalline, transparent, bluish purple variety that is properly
called a gem-mineral rather than a gemrock. Nontheless, it seems
noteworthy here that soon after the
11th (2001) attacks, word was spread around the marketplace that sales
helped fund Osam bin Laden and the Al-Quaeda network. And, as a
several jewelers, especially in the United
States, imposed a boycott on further imports of the gem,
and some of them even removed tanzanite-bearing jewelry from their
Subsequently, however, the U.S. State Department said that no evidence
tie sales of tanzanite to funds supporting the Al-Quaeda, and
many jewelers lifted their boycott (etc.).
REFERENCES: No general
reference. Abrecht, 1981. Gübelin, 1969. Keller, 1992.
| Top | Home |
R. V. Dietrich © 2014
update: 4 July 2005
web page created by Emmett Mason