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Green zircon
This is a relatively common stone, but may vary
a great deal in its characteristics, the green color generally
being associated with the metamict state.
Appearance The color varies from a slightly
brownish green to brilliant rather cold green, or yellow green.
Spme examples are perfectly transparent; others can look cloudy
and display close, parallel striations, which are the main
signs of the breakdown of the crystal lattice. The luster
is affected by this turbidity and is often much less strong
than in other zircons. The same is true of the birefringence,
which is obvious in the clearer, more lustrous green zircons,
but hard to see in the others. The oval or round, mixed cut
is the most common. The edges are easily damaged, especially
those of the cloudier stones, which are not so hard.
Distinctive features Clear, lustrous stones
still display some birefringence. In cloudy specimens, this
is not visible, but the appearance and presence of striations
are equally characteristic. In either case, it is fairly easy
to distinguish green zircon from green sapphire, but rather
harder to tell it from olivine and some green tourmalines.
Green zircons with good luster and clearly visible birefringence
(thus with high density and refractive indices) may display
the physical properties of high zircon, but the density, refractive
indices and birefringence are often lower, considerable variation
being possible. Despite the metamict process, the absorption
spectrum is usually quite disAbove: Brown zir- tinctive.
Occurrence Most green zircons come from Sri
Lanka. Below: Green zircon. Greenish to brownish-green specimens
are also found in 174
Burma.
Value Comparatively low, about the same as
that of yellow zircon. Stones with inferior luster are even
less valuable.
Simulants and synthetics Being of low value,
it has neither been imitated nor produced synthetically.
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