On the analytical determination of the optical indicatrix of anhydrite

Abstract

Chomard's analytical method was applied to the determine the magnitude of anhydrite optical indicatrix, based on a theoretical development from the authors' earlier paper. The λ and µ λ = (Ng - Np)/2 values, needed for the calculation of Np, Nm and Ng were calculated in several different ways. A comparative study of the results led to the following main conclusions: the values are too discrepant, while the µ λ values are practically constant for all the methods of calculation used. Furthermore, the determination of the principal refraction indexes is not feasible, since it requires a precision in the birefringence measurements that is impossible to obtain with the means presently available.