Typically sourced from Madagascar , Canada (Labrador), and Finland (Spectrolite variety), this is a sodium-calcium plagioclase feldspar , intermediate between andesine and bytownite. It forms by magmatic crystallization in mafic igneous rocks (gabbro, anorthosite) during the Precambrian to Phanerozoic. It displays the characteristic “labradorescence” optical effect caused by light interference on submicroscopic exsolution lamellae. Hardness 6–6.5 Mohs, density 2.68–2.72 g/cm³.
Widely used in jewelry and as an ornamental stone for its iridescent color play; prized
by collectors for specimens with strong blue-green “flash”; also used as a decorative facing stone in architecture.