INTRODUCTION | WHAT IS IVORY? | THE IVORIES | IDENTIFYING IVORY | GLOSSARY

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NATURAL IVORY SUBSTITUTES

• Bone and Shell
• Helmeted Hornbill
• Vegetable Ivory

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BONE AND SHELL

Bone
Bone is a mineralized connective tissue consisting of dahllite, proteins and lipids. Compact bone, which is most often used as an ivory substitute, is extensively permeated by a series of canals through which fluid flows. This is the Haversian System. The Haversian canals can be seen on a polished bone surface using a 10X hand lens. These canals appear as pits or scratch like irregularities. Their appearance is often accentuated by the presence of discolored organic material which adheres to the pit walls.

Click to see photomicrograph of bone

Shell
Shell is a calcium carbonate found as the protective covering of a soft bodied mollusk. Shell can be polished to a very smooth hard surface. Shells may present color mottling, which persists through ultraviolet examination. In the absence of gross morphological features, identification of shell is best done by FT - IR.

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HELMETED HORNBILL

(Rhinoplax vigil)

The casque of the endangered Helmeted Hornbill, a native of Borneo, can be carved and polished. The casque is a hollow, roughly cylindrical attachment to the bird's upper bill. The casque is distinctive by virtue of its size, up to approximately 8 x 5 x 2.5cm, and its peripheral color, which is a bright red. Other names for Hornbill casque "ivory" are "hot-ting" and "golden jade".

Click to see hornbill "ivory"

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VEGETABLE IVORY

(Phytelephas macrocarpa)

Vegetable ivory or ivory nuts are primarily the nuts of the Tagua palm tree (Phytelephas macrocarpa) although other palms of the same subfamily also produce ivory nuts. Tagua trees grow mainly in moist locations in northern South America. The mature nut, which can reach the size of an apple, has a very white, exceedingly hard cellulose kernel, which is worked like ivory. The husk of the nut has a dark brown appearance and is frequently incorporated into the carving.

Examination of the cellulose in carved vegetable ivory reveals a series of fine, regularly spaced concentric lines similar to those seen in the hippopotamus. Close examination with a low powered microscope reveals a grainy or lined appearance. These features may not always be obvious on highly curved surfaces. Vegetable ivory UV fluorescence is very similar to ivory fluorescence. In the absence of morphologically identifying features, identification of vegetable ivory is best done using FT-IR. Perhaps one of the oldest field tests for differentiating vegetable ivory from real ivory is the addition of sulfuric acid to the item to be examined. Sulfuric acid applied to vegetable ivory causes an irreversible pink coloring in about 12 minutes. Genuine ivory should not stain.

CAUTION: Due to the irreversible nature of this test, only a minute dot of acid should be applied to the object in question.

Click to see cross section of a taguanut

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