Gem and Ornamental

58 GaMs AND ORNAMENTAL MIXRIMS OF ORGANIC ORIGINFigure 3.1 Young &anelephant. Tanzania.Elephant mks are upper incisom embedded deep in sockets in theupper jaw. From the age of about two years when the deciduous tush(millr tusks) fall out, the mature tusks grow throughout the life of theanimal. They grow in a gentle, downward then upward curve and aresolid almost throughout their length. There is pulp cavity only in thesection of tusk that is within the jawbone. There is little if any enamelcwering, and this is co&d to the tip. The tusk is almost cyindridand is covered in a narrow layer of p b dentine. Inside ~ s in , crosssection,the & bulk of the dentine shows the typical 'engine turning'or cross-hatching pattern that is unique to elephant or mammothivories (Figs 3.2 and 3.12). This is a series of intersecting arcs awedby the in- structure of the dentine, In longitudinal section the arcsappem as uneven, slightly wavy lines. This wavy pattern of lines anappem on other ivories md is not conhed to elephants andmammoths. ivory is a pale, creamy colour, while Asian is a