Mint tourmaline is the trade descriptor for light bluish-green to mint-green tourmaline, almost always elbaite, the lithium-bearing tourmaline species that produces the gem trade's most colourful varieties. Mint tourmaline sits at the pastel end of the elbaite green spectrum, distinct from the more saturated chrome tourmaline of East Africa and from the cuprian Paraíba tourmaline of Brazil and Africa, but visually adjacent to both.

Colour and chemistry

The mint-green colour in elbaite comes principally from trace iron, with some material owing additional colour modifier to copper. True cuprian mint tourmaline — copper-coloured pastel green that meets the analytical and inclusion criteria for Paraíba designation — is occasionally encountered from the African deposits at Mavuco, Mozambique, and from the Nigerian and Brazilian fields. Most stones marketed simply as mint tourmaline, however, are iron-coloured and do not qualify for the Paraíba designation set out by the LMHC (Laboratory Manual Harmonisation Committee).

Refractive index for elbaite runs approximately 1.62 to 1.65, with strong birefringence; hardness is 7 to 7.5 on the Mohs scale; specific gravity around 3.05.

Sources

Mint elbaite has been produced from pegmatite fields across the world. Notable production has come from the Paprok and Nuristan pegmatite fields of Afghanistan, the Nigerian fields of Oyo and Plateau states, the Mozambican deposits at Mavuco and the Alto Ligonha district, and the long-running Brazilian production from Minas Gerais. Each source has subtle differences in colour shade and inclusion picture.

Pricing

Pricing for mint tourmaline ranges widely. Iron-coloured pastel material in commercial sizes runs from approximately fifty to two hundred dollars per carat; clean, well-saturated stones can reach five hundred dollars per carat. True copper-coloured cuprian mint tourmaline meeting Paraíba designation criteria commands prices many multiples higher, in the thousands of dollars per carat.

In the trade

Skyjems treats mint tourmaline as a descriptive trade term rather than a varietal name. The varietal classification is elbaite; the colour-source classification (iron versus copper) requires laboratory analysis. For any stone where Paraíba designation would meaningfully affect price, the seller should commission an LMHC-aligned report from a recognised laboratory.

Further reading

• GIA — Tourmaline reference
• GIA Gems & Gemology — Paraíba and elbaite articles
• ICA — coloured stone reference