Andesine-LabradoriteVSLabradorite

◆Standard labradorite (plagioclase feldspar in the An50–An70 composition range, Mohs 6–6.5, SG 2.69–2.72, RI 1.560–1.572, biaxial doubly refractive, characteristic spectral labradorescencechiller' from internal albite-anorthite lamellae, typically translucent grey body without strong colour) versus the copper-coloured andesine-labradorite variety (same species range, same Mohs 6–6.5, same SG 2.65–2.74, same RI 1.543–1.573, but with colloidal-copper red-pink chromophore replacing the colourless or grey body). The compositional and structural identity means standard gemological tests (refractometer, polariscope, hardness, density) do NOT distinguish standard labradorite from copper-coloured andesine-labradorite — the only distinction is the chromophore and the colour. The diagnostic test for diffusion-treatment versus genuine untreated copper coloration requires LA-ICP-MS trace-element fingerprinting and UV-Vis-NIR spectroscopy at SSEF/GIA/Lotus Gemology. Standard labradorite from Labrador Canada (the type locality, named 1770 by Moravian missionaries at Nain), Finland (Spectrolite, Ylämaa), Madagascar, and Russia trades at $5–$50 per carat for the characteristic labradorescence schiller material; copper-coloured andesine-labradorite at the same Mohs and SG levels carries the treatment-disclosure question and the corresponding declared-treatment pricing.