CUPRIAN LIDDICOATITE TOURMALINE

Cuprian (copper-bearing) tourmaline, known as Paraiba tourmaline in the trade, has been an important gem since its discovery in 1989. Until now, almost all of the material reported has been classified as the elbaite species of the tourmaline supergroup. Chemical analyses by laser ablation-inductively coupled plasma-mass spectroscopy (LA-ICP-MS), a common technique for origin determination of Paraiba tourmalines, revealed that 13 copper-bearing samples submitted to GIA's Tokyo laboratory contained substantial amounts of Ca in the X-site. Consequently, they are classified as liddicoatite tourmaline. The origin of these stones is unknown.