Mint garnet is the trade name for light bluish-green to mint-green grossular garnet, most famously from the Merelani Hills of northern Tanzania — the same deposit that produces fine tanzanite. The colour comes from trace vanadium with low iron, the same colouring scheme that produces tsavorite at higher saturation. Mint garnets sit at the pastel end of the green-grossular spectrum, complementing tsavorite rather than competing with it.

Composition and properties

Mint garnet is grossular, Ca₃Al₂(SiO₄)₃, with the colouring trace element vanadium responsible for the green hue. Iron, which would push the colour toward yellow-green or olive, is characteristically low in mint material. The species is cubic, with a refractive index in the 1.73 to 1.74 range, hardness 7 to 7.5 on the Mohs scale, and specific gravity around 3.6.

Mint garnets are typically eye-clean. Inclusions, where present, are most often small healed fissures or rare crystal inclusions of host-rock minerals.

Sources

The Merelani Hills in the Lelatema Mountains of Tanzania are the principal source of fine mint grossular. The deposit is the same metamorphic graphite-bearing terrain that hosts tanzanite (blue zoisite) and a range of other coloured stones. Smaller production comes from related East African sources in Kenya and from Madagascar. Pakistan and Mali have produced occasional mint-coloured grossular as well.

Sizing and pricing

Stones above five carats in fine pastel mint colour are uncommon and command meaningful premiums. Most fine mint material on the market sits in the one-to-three carat range. Prices for fine commercial-grade material run under two hundred dollars per carat; exceptional larger stones with strong saturation can reach considerably higher.

Design context

Mint garnet has found a strong audience in contemporary designer jewellery for its pastel palette and its compatibility with both white and yellow metals. The colour reads fresh and modern against either tone and pairs well with diamonds, white sapphires, or aquamarine. The absence of the deep saturation of tsavorite is, for many designers, a feature rather than a limitation.

In the trade

The relationship between mint garnet and tsavorite is one of degree rather than kind. Both are vanadium-coloured grossular; mint stones simply have lower colour saturation. Some dealers reserve tsavorite for the saturated material and use mint garnet or Merelani mint for the lighter stones. Skyjems treats the categorisation as descriptive rather than strict and considers each stone on its own merits of colour, clarity, cut, and size.

Further reading

• GIA — Garnet reference
• GIA Gems & Gemology — grossular and Merelani articles
• ICA — coloured stone reference