Golden Jade – Hornbill Ivory
A Treasured Carving Material Comes from the Helmeted Hornbill
Nov 7, 2009
Hornbills, striking birds of Africa, Asia, and Indonesia, often have a casque, or epithema, on their upper bill. In most species the casque is hollow, but in one species, the Helmeted Hornbill (Rhinoplax vigil), it is a solid structure that makes a good material for carving. This is hornbill ivory, also known as golden jade, hoden, or ho-ting.
Hornbill ivory is sometimes written hornbill “ivory,” because this material is not true ivory.
Types of Ivory – What is Golden Jade?
The word ivory literally refers to the tusks of elephants or the tusks or teeth of various other animals such as the walrus. True ivory is mostly composed of the mineral calcium phosphate, and is a pale off-white colour.
Golden jade, the material that comes from the casque of the Helmeted Hornbill, is keratin, a tough protein that also forms the main material in finger- and toenails, claws, hair, horns, hoofs, and even the outer layer of human skin cells. Though not living tissue (there is no blood supply) these structures are organic: they are produced by living bodies and are important for protecting parts of the body that endure a lot of wear.
Golden jade doesn’t look like true ivory: it ranges from yellowish through golden and brown, and often has a relatively thin outer layer coloured with shades of red. It is semitransparent in thin layers, dull to pearly in thicker pieces, and slightly brittle. It can be polished to a smooth lustrous sheen.
The Helmeted Hornbill and Hornbill Ivory
Rhinoplax vigil is found in Southeast Asia and Indonesia, particularly in tropical lowland forests and forested foothills. It is a black (or brown) and white bird with very long tail feathers, and the male has a beak that appears massive because of the bulky casque that sits above the beak and eye. Because it is solid keratin, the casque is indeed heavy, and the head of the bird accounts for a full tenth of its total weight.
The beak, casque, and bare skin of the throat are brightly coloured in shades of red, orange and yellow. As in other hornbills, these bright colours aren’t part of the tissue but are actually pigments applied when the hornbill rubs its head and beak on its preen gland: the preen oil is the source of the colour. The cosmetic application explains why the colour is only a thin layer near the surface of the casque, and probably accounts for the variation in colour from one bird to another, and any variation in shading.
Hornbill ivory is not only prized as a material for carving, it is also considered an aphrodisiac in some cultures, and many believe that it will change colour when exposed to poisons. The best golden jade is obtained from young adult male birds, a fact that accounts for the steady decline in the species. Rhinoplax vigil is now listed as “near threatened” on the IUCN Red List of Threatened Species.
History of Golden Jade in Human Cultures
People have been collecting and carving hornbill ivory since the late Stone Age (about eight thousand years ago in Southeast Asia). Indigenous cultures of Indonesia carved it into jewelry and other decorative pieces, and traded it to the Chinese. Some artisans take advantage of the red outer surface and translucence of golden jade by carving away the material under the coloured layer, leaving a few connections to hold the piece together, and thus creating a three-dimensional carving that light can pass through.
Today, because both hunting and the loss of forest habitat threaten the survival of the Helmeted Hornbill, trade in hornbill ivory is banned, indigenous cultures are encouraged to avoid killing the birds, and antique carvings in golden jade are rising in value.
Sources
Firefly Encyclopedia of Birds. Perrins, Christopher ed. Buffalo: Firefly Books, 2003
“Rhinoplax vigil (Helmeted Hornbill).” IUCN Red List of Threatened Species. iucnredlist.org
"Hornbill 'Ivory.'" Dietrich, R. V. Central Michigan University. cst.cmich.edu
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