Lapa tourmaline refers to elbaite tourmaline from the Lapa pegmatite area of Minas Gerais, Brazil, principally from the Cruzeiro and adjacent mines worked since the nineteenth century. The Lapa name in the trade is associated with intense blue indicolite material, although the workings have also produced fine green, pink, and bicolour tourmaline. The state of Minas Gerais is by some distance the world's most productive elbaite source, and the Lapa workings are part of the broader Eastern Brazilian Pegmatite Province that also yields the Paraiba-type cuprian tourmaline, morganite, kunzite, and aquamarine.

Mineralogy and colour

Lapa indicolite is iron-bearing elbaite in which Fe²⁺ in octahedral sites contributes the characteristic blue. The colour ranges from a teal-leaning blue-green to a saturated, slightly violet blue. Strong dichroism is typical, with the deeper blue along the c-axis and a lighter, sometimes greenish blue perpendicular to it. Cutters orient the stone to favour the deeper colour through the table while controlling tone by choice of length-to-width ratio. Heat treatment to lighten over-dark indicolite and to remove residual brown components is routine in the trade and should be disclosed under AGTA and CIBJO conventions.

Working and durability

Tourmaline rates 7 to 7.5 on the Mohs scale and is durable enough for daily wear. Lapa indicolite, like many tourmalines, frequently contains feathers and tubes parallel to the c-axis (the trichite inclusions characteristic of the species), and cutters favour shapes that put the long dimension parallel to c to maximise yield. The pyroelectric and piezoelectric properties of tourmaline mean that mounted stones can attract dust under temperature change, which is a curiosity rather than a durability issue.

Trade context

Lapa indicolite competes with Afghan, Pakistani, Namibian, Mozambican, and the new Nigerian indicolite finds. Brazilian material has historically commanded a premium for very clean, large stones in saturated blue, although the recent Mozambican and Nigerian discoveries have narrowed that premium. The trade convention is to record origin where it can be substantiated by trusted laboratory report; a Brazilian-origin call from GIA, GRS, AGL, or SSEF carries weight, while uncorroborated dealer attribution does not.