TITLE:
Investigation Of Hardness Anisotropy In Tourmaline
AUTHORS:
M.O. Adeoye, O.O. Adewoye
KEYWORDS:
Tourmaline, Hardness anisotropy, Microhardness, Knoop
JOURNAL NAME:
Journal of Minerals and Materials Characterization and Engineering,
Vol.3 No.2,
October
20,
2004
ABSTRACT: Tourmaline is a ring silicate material with a hexagonal crystal structure. Tourmaline crystal is made use of as an electronic component, e.g, as a transducer, mainly because of the anisotropy it exhibits in its properties. Microindentation technique was employed in the research reported in this paper, using a Knoop indenter, to investigate the anisotropy in the hardness of the tourmaline crystal on its two major crystallographic planes: (0001) and {10 1 0}. The material was found to exhibit hardness anisotropy in conformity with its rotary symmetry elements.
The material was identified and analysed using various x-ray techniques, and was found to contain some impurities as expected of natural crystals. Tourmaline was found to have a Si/Al ratio of 1.4. The orientations of the crystal samples were determined by obtaining and indexing the Laue x-ray back-reflection patterns of the crystal samples.