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Ivory
Distinctive
features Ivory's chief characteristic is its fir
grain, distinguished from the background only by a sligrincrease
in translucency, best seen in strong light, z though barely
visible, if at all, on the natural outer surfac of the tusks,
where this has been preserved. This readii. distinguishes
it from bone, which has a heterogeneous nevwork of markings,
although this is only visible under a m - croscope. Plastic
imitations of ivory have, at the most, th - superficial furrows
which crudely imitate the longitudin~ grain and these melt
and scorch visibly if touched with th= tip of a thin piece
of red-hot wire. Ivory also turns black and gives off a smell
of burning protein when burned, bu' the prevalence of the
organic component gives it fagreater resistance than any type
of plastic. If necessary measurement of the density is also
very useful for distinguishing ivory from its imitations.
Occurrence As mentioned above, most ivory
come, from various parts of Africa (mainly Cameroon, Gabon
Zaire, Ghana, Sierra Leone, Angola, Tanzania, Mozambique,
and Zimbabwe) and Asia (mainly India, Thailan(I and Burma).
Value The price of ivory has risen again recently, but as
with jade, very much depends on the quality of the work manship,
which can be outstanding because of the intrinsicqualities
of the material. When the workmanship is excellent, the value
of ivory may equal that of other prized ornamental materials,
including jade. But when the work is more commonplace, its
value is much lower, although it will still be higher than
that of small, mass-produced objects in. say, nephrite jade.
Simulants Ivory was and is widely imitated
by all types of plastics. Among the moulded objects produced
are some which are far too large to have come from a single
piece of ivory, as, for instance, small tables with a carved
central pedestal. Sometimes, complete carved tusks have been
made out of these plastics, which are very hard to distinguish
from the real thing, at least with the naked eye. Many umbrella
and walking-stick handles made earlier in the twentieth century
are also of plastic, as are dressing table sets of the same
period. All these imitations generally have a lower density
than that of ivory, but much higher than thal. of transparent
plastics, inert mineral powders having beer incorporated in
them to add to their credibility
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