Table of Contents
Textures and Microstructures
Volume 26–27

Correlation Between Texture of Hydroxyapatite and Mechanical Anisotropy in Loxodonta Africana Ivory

1Atomic Energy Corporation, PO Box 582, Pretoria 0001, South Africa
2Dental Faculty, MEDUNSA, South Africa

Received 18 December 1995

Copyright © 1996 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Samples of Loxodonta africana ivory were subjected to X-ray diffraction studies which showed that the hexagonal crystals have a strong preferred orientation with their basal planes perpendicular to the longitudinal axis of the tusk. Cylindrical samples were also machined from the tusk with cylinder axes along and perpendicular to the longitudinal axis of the tusk respectively. Three-point bending tests were performed on the cylindrical samples. The results show a clear anisotropy in the bending strength along the two directions. The sample with cylindrical axis longitudinally aligned shows less bending for the same applied force. The results verify a correlation between orientation of hydroxyapatite and, among other things, the mechanical strength. This may be related to the function of the tusk which with normal usage has to be able to sustain large bending forces in a direction normal to the longitudinal axis.