Watermelon Tourmaline and Quartz

WATERMELON TOURMALINE AND QUARTZ  

São José da Safira, Minas Gerais, Brazil

specimen: 8 x 5 x 6 1/2 inches (20.3 x 12.7 x 16.5 cm)  

height with stand: 8 1/2 inches (21.6 cm)

The distinctive zoning of watermelon tourmaline is a direct record of the crystal's growth history: shifts in the chemical composition of the host pegmatite — from iron- and manganese-dominated conditions, producing green elbaite, to lithium-rich conditions, producing pink rubellite — are preserved as concentric bands within each crystal. The gem pegmatites of Minas Gerais are the world's foremost source of fine watermelon tourmaline, and São José da Safira among the most productive localities for large, well-formed specimens.

A cabinet specimen presenting a vertical cluster of elongated prismatic tourmaline crystals displaying the characteristic concentric pink-and-green zoning that gives watermelon tourmaline its name, set on a matrix of smoky quartz. The bi-coloured crystals are visible from multiple aspects.