The Gladstone-Dale rule, which is an empirical attempt to relate chemical composition, refractive indices, and density, was applied to minerals by Larsen in 1934. In 1956, Jaffe offered some corrections and additions to Larsen's original constants.

While applying the Gladstone-Dale relationship to some tellurites and selenites this writer found that Larsen's constants for TeO₂ and SeO₂ required revision. Furthermore, the value of these constants, as well as those for many other oxide components, varied widely, depending on the particular compounds used to calculate them.

Values of k for various oxide components are given here, using Larsen's form of the Gladstone-Dale equation:

[EQUATION]

In this equation, n is the average index of refraction, d is the density, k is the specific refractive energy for a particular oxide component, and p is the weight percentage of the component.

Table

Users of the Gladstone-Dale relationship should realize that wide differences between calculated and observed refractive indices and densities may be caused by the variation in k values.

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