Origin of color in cuprian elbaite from São José de Batalha, Paraíba, Brazil

Gem-quality elbaite from Paraíba, Brazil, containing up to 1.4 wt% Cu has been characterized using optical spectroscopy and crystal chemistry. The optical absorption spectra of Cu²⁺ in these tourmalines consist of two bands with maxima in the 695- to 940-nm region that are more intense in the E ⊥ c direction. The vivid yellowish green to blue-green colors of these elbaite samples arise primarily from Cu²⁺ and are modified to violet-blue and violet hues by increasing absorptions from Mn³⁺.