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Unlike ivory, which has no marrow or blood vessel system, bone has a spongy central portion of marrow from which extend tiny blood vessels; bone is therefore highly porous. Bone is also made of both mineral and carbon-based materials; the mineral-based are calcium, phosphorus, and fluoride; the carbon-based is the protein ossein.
Visual examination is a very useful method to identify ivory. By using the characteristics of the variety of ivories listed about in addition to images and samples often they type of ivory can be identified. It is helpful to consider the size of the object, if it is a long and uninterrupted section it is may be elephant or mammoth.
Ivory's mechanical properties result from the microstructure of the dentine tissue. It is thought that the structural arrangement of mineralized collagen fibers could contribute to the checkerboard-like Schreger pattern observed in polished ivory samples. [1] This is often used as an attribute in ivory identification.
Bone, Antler, Ivory & Horn: The Technology of Skeletal Materials Since the Roman Period. Barnes and Noble, 1985. [Reprinted 2016, Routledge] This is a scholarly monograph on the subject of horn and other skeletal materials, heavily illustrated, and with extensive academic and art-historical references.
Growth occurs at the tip, and is initially cartilage, which is later replaced by bone tissue. Once the antler has achieved its full size, the velvet is lost and the antler's bone dies. This dead bone structure is the mature antler. In most cases, the bone at the base is destroyed by osteoclasts and the antlers fall off at some point. [6]
Ivory is a fragile medium; many 19th-century pieces were preserved because they were kept in a barrel of oil on board ship. Gary Kiracofe, a scrimshander in Nantucket, Massachusetts, advises collectors that if a piece looks dry, one should fill the center of the tooth with unscented baby oil and allow it to remain until as much oil as possible is soaked into the microscopic pores of the ivory.
Walrus ivory, also known as morse, [1] comes from two modified upper canines of a walrus. The tusks grow throughout life and may, in the Pacific walrus, attain a length of one metre. [ 2 ] Walrus teeth are commercially carved and traded; the average walrus tooth has a rounded, irregular peg shape and is approximately 5 cm in length.
Schreger lines in a mammoth ivory. Schreger lines are visual artifacts that are evident in the cross-sections of ivory. [1] They are commonly referred to as cross-hatchings, engine turnings, or stacked chevrons. Schreger lines can be divided into two categories. The easily seen lines which are closest to the cementum are the outer Schreger lines.