Bastnäsite

Refractive Index: 1.7200
Abbe Number: 30.0
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 REE carbonate analogy)

Cauchy approximation

Valid 0.38–0.78 µm

$n$

n

= 1.7200

V_{D}

= 30.0

n (λ) = 1.6838 + 0.012563/ λ^{2}

REE fluorocarbonate. Dispersion estimated from analogous REE minerals. n_D from published gemological tables; V_D estimated from REE carbonate analogy because species-specific dispersion is not widely reported. Source: Winchell / GIA / Liddicoat compilations.

Absorption Specimens