Calculate the refractive index using the Gladstone–Dale approach for orthoclase of Problem 15.9 using the chemical refractivities from Table 15.1. Compare the result with that of Problem 15.9.

Problem 15.9

Use the Anderson–Eggleton relationship to calculate the refractive index of the mineral orthoclase (KAlSi₃O₈) with a unit-cell volume 720.4 ų containing four formula units. The cation polarizabilities are 1.35 ų, 0.533 ų, and 0.284 ų, for K+, Al³⁺, and Si⁴⁺, respectively. The free-ion polarizability α0 for oxygen is 1.79 ų and N₀ is 1.776 ų.

Table 15.1

Transcribed Image Text:

LiO NaO KO Rb0 C$0 0.307 0.190 0.196 0.128 0.119 MgO CaO SrO BaO 0.200 0.210 0.145 0.128 0.133 B03 AlO3 POs A$05 SiO 0.215 0.207 0.176 0.340 0.208