Orthoclase

Moonstone

Refractive Index: 1.5220
Abbe Number: 60.0
Crystal System: Isotropic (cubic)
Formation: Natural
Dispersion Data: Approximate (from n, V)
Fits: 1

Refraction Fits

Fit #1— Cauchy from (n_D, V_D)

Cauchy approximation

Valid 0.38–0.78 µm

$n$

n

= 1.5220

V_{D}

= 60.0

n (λ) = 1.5089 + 0.004554/ λ^{2}

Adularescent orthoclase. RI and dispersion identical to orthoclase parent; the moonstone effect is structural (exsolution lamellae). Source: GIA / Winchell / Liddicoat gemological tables.

Absorption Specimens

Sri Lanka, Southern Province, Meetiyagoda