Gem and Ornamental

HORN 109the horn forms a sheath covering a bony core, which is attached to thehntal bones of the animal's skull. Horns are permanent smmures,which grow continuously throughout the animal's life.The colour in horn comes &om the pigment melanin. The colwrvaries from cream through bmwns to black, or can be a mixture ofthese colours, depending on the species.All types of horn are waterproof and greaseprod, and cau be madeinto items that are airtight. The material is also thermoplastic so canbe heated and moulded, retaining its ahape after cooling.Now Baleen (see Chapter 12, 'Miscellaneous e c s ' ) and hoof arevery d a r to horn and have in past times been put to many of thesame uses. They are a h made of keratin, but me solid. Eke horn,hoof also consists of lamhuted layers of keratin, The structure ofbaleen is dilkent: it consists of very h e tubes of keratin, held togetherby a coating of the same material.It can be difEcult, if not impossible, to tell whether a fished itemhas been made from hoof, baleen or horn. The shape of the hisheditem may give some indication as to im origin, as the natural shape will,to wme extent, iduence how the mated is fu&ioned.Derived hm wWa1 baleen is no longer used today. Hoof is usedmostly for the production of gelathe or fertili~er.THE SPECIESAny horn can be used to malce items of jewellery, boxesl and countlessother objects, and there are examples of weird and wonderful itemsFigure 7.1 Water ln&lo in V i m .