Feature
Gems & Gemology, Winter 2001, Volume 37, No. 4
An Update on “Paraíba” Tourmaline from Brazil
James E. Shigley, Brian C. Cook, 和 Brendan M. Laurs, Marcelo de Oliveira Bernardes
Vivid blue, green, and purple-to-violet cuprian elbaites, renowned in the gem trade as “Paraíba” tourmalines, continue to be recovered in small amounts from northeastern Brazil. Since the initial discovery of this copper-bearing tourmaline in 1982, production has been sporadic and has not kept up with the strong market demand. Mining currently takes place at the original discovery—the Mina da Batalha—and at adjacent workings near São José da Batalha in Paraíba State. At least two pegmatite localities (the Mulungu and Alto dos Quintos mines) in neighboring Rio Grande do Norte State have produced limited quantities of cuprian elbaites. All of these pegmatites occur within Late Proterozoic metamorphic rocks of the Equador Formation; the source of the copper is unknown. Six blue to blue-green elbaites from Mulungu had lower copper contents (up to 0.69 wt. % CuO) than the brightly colored Mina da Batalha material reported in the literature.
