Powellite

Refractive Index: 1.9800
Abbe Number: 25.0
Crystal System: Isotropic (cubic)
Formation: Natural
Dispersion Data: Approximate (from n, V)
Fits: 1

Refraction Fits

Fit #1— Cauchy from (n_D, V_D estimated from scheelite analogy)

Cauchy approximation

Valid 0.38–0.78 µm

$n$

n

= 1.9800

V_{D}

= 25.0

n (λ) = 1.9209 + 0.02052/ λ^{2}

Ca molybdate; scheelite-group. Dispersion estimated. n_D from published gemological tables; V_D estimated from scheelite analogy because species-specific dispersion is not widely reported. Source: Winchell / GIA / Liddicoat compilations.

Absorption Specimens