Chemical composition -- An organic gem material composed primarily of calcium carbonate (calcite ). Both are derived from the skeleton of mammals -- ivory from the tusks of elephants, walrus, hippopotamus, wart hogs, and sperm whales, and bone usually from cattle or oxen. Formerly prized for carvings, piano keys, and other items, ivory has been widely banned over the past couple of decades due to the risk of extinction of its donor species. Ancient, fossilized ivory is sometimes seen. Bone is widely used as a substitute for ivory, as is so-called vegetable ivory or tagua nut.
Scrimshaw is the traditional art of painting on ivory or ivory substitutes. Fine lines are incised on the
surface of the material and then painted over with colored inks. Scrimshaw on whalebone or whale ivory
was popular especially among North American whalers in the 19th and early 20th centuries.
Color --White to yellowish. Ivory tends to yellow with
age and takes on a mellow brownish-yellow patina.
Optics -- R.I. 1.54.
Durability -- Hardness 2.5. Tough. Workable with ordinary steel cutting tools.
Crystal structure -- Ivory has a distinctive, "engine-turned" cellular appearance under magnification.
Specific Gravity -- 1.7-2.0.