SEDL / STP / STP431-EB / STP45167S

3-5 Mineral Cleavage and Cohesive Strength of Single Crystals

DeVore, George W.
Florida State University,

Pages: 1    Published: May 1967

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Abstract

The relationship of fracture stress to Young's modulus, surface energy and atomic separation that has been used successfully for NaCl, diamond and glasses is applied to the interpretation of cleavage and parting in silicate single crystals. If modulus of rigidity is substituted for Young's modulus in the fracture stress equation, improved correlations between cleavage directions and directions of low or minimum values for the rigidity modulus result. If the elastic moduli and the atomic separations are known for a crystal, the relative surface energies for the different crystallographic directions may be estimated from the cleavage relations. A Griffith crack mechanism for cleavage should yield the same cleavage directions but at lower stresses.