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Decorative
Stones
Malachite and Azurite
Malachite is an important copper ore that also makes
an attractive gemstone. It has been known and used in
jewelry since the days o ancient Egypt, as early as
4000 B.C. For millennia it was considered a ¬magical
stone with potent powers. Crystals are rare and highly
esteemed among mineral collectors. Massive banded material
is much more abundant, notably from Zaire. Other localities
for malachite include France, England, Rhodesia, New
Mexico, and Arizona. In maw localities malachite, which
is always some shade of green, is mixed with blue azurite.
Both minerals are copper carbonates.
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Their
association Is ¬widespread, and azurite is frequently
found altering to malachite. Azu¬rite is seldom
used for gem purposes, and massive deposits of it, com¬parable
to those of malachite, do not exist. |
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Malachite
is soft, only 31/2-4 on the Mohs scale; the same is true of
azurite. Both minerals take a high polish, but the polish
is lost relatively. quickly with wear, due to scratching.
Massive banded material is den, and compact, but is not very
tough and should always be set and worn ¬with great care.
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DIAMONDS,
GEMSTONES & CRYSTALS
FACTS & FIGURES |
| Malachite
is customarily made into beads, cabochons, and
a variety, ¬of carved shapes, such as figurines
and ashtrays. Large deposits of very fine banded
malachite in the U.S.S.R. found use in buildings,
and whole rooms in certain palaces were lined
with malachite slabs. Russia workmanship in this
gem is unsurpassed.Chrysocolla Chrysocolla is
a hydrated copper silicate.
It
forms as an alteration duct in copper deposits,
in veins and cracks, or as a coating on rocks.
Sometimes it accumulates in sufficient thickness
to be cut into gem¬stone. More frequently
Chrysocolla merely stains chalcedony, produc¬ing
an intense blue material that is also tough and
durable. The color of Chrysocolla depends on its
purity, and ranges from pale blue to dark blue-green,
and yellow-green. The finest material is translucent,
uniform blue in color, and free of off-color spots.
The hardness of Chrysocolla is only 2-4 on the
Mohs scale, but the material frequently contains
enough silica to become hard, and it will then
take a high polish. Localities for Chrysocolla
include Nevada, New Mexico, Arizona, Chile, and
the U.S.S.R.
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Variscite
Variscite
is an aluminum phosphate with a lovely yellow-green
to e-green color. It commonly forms nodules associated
with other phosphate minerals, in intricate banded
and patterned textures. The hardness is only 4-5
on the Mohs scale, and the material is neither
tough - durable. The only important localities
are in Utah, where the nodules can reach diameters
up to 1 foot. The usual form of cutting is cabochons
and polished slabs. Some tradenames applied to
Variscite in the past include "amatrix,"
for American matrix, "Nevada turquoise "California
turquoise," and "Utahlite." Amatrix
is a mixture of Variscite in quartz or chalcedony,
and so somewhat harder than pure Variscite. |
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Sodalite
Sodalite is an attractive, deep-smalt-blue mineral, chemically
con, posed of sodium aluminum silicate. Crystals are extremely
rare, but massive material is abundant in certain localities.
Sodalite is one of the mineral components of the rock lapis
lazuli, but became an important ornamental material in its
own right when large deposits were found in Ontario, Canada.The
hardness of Sodalite is 5 1/2-6 on the Mobs scale, which is
adequate for the cabochons and beads usually fashioned from
the ¬material. Slabs are also polished and used in inlaid
boxes and clock, Canada is the most important source, but
other localities include Nor¬way, India, Maine, and Massachusetts.
A beautiful, almost transparent blue Sodalite comes from South
West Africa.
Socialite is quite inexpensive, and hobbyists can obtain rough
mate¬rial at a cost of several dollars per pound. Large
blocks of Sodalite are 110 frequently cut into animal figures
and other decorative shapes.
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