1972•physica status solidi (a)Requires access
Study of exsolution in alkali feldspars calculation of elastic stresses inducing periodic twins
Christian Willaime, M. Gandais
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Abstract
Exsolutions in alkali feldspars were observed by electron microscopy and diffraction. Lamellae of more potassium-rich monoclinic feldspar and lamellae of more sodium-rich triclinic feldspar are seen. These sodic feldspar lamellae show twin bands with a direct relation between the width of the lamellae and the period of the twins. This relation is physically established by calculation of the strain energy in triclinic feldspar near the boundary plane with monoclinic feldspar. This relation is in good agreement with the experimental data. The surface energy in albite twinning is calculated to be 0.42 erg/cm2.