Emerald at the Tsa da Glisza property in southeast Yukon is associated with abundant quartztourmaline veins within chromium-rich mafic metavolcanic rocks. A genetic model for the emerald mineralization has been formulated: vein fluids were mixtures of fluids from both magmatic and metamorphic sources. Beryllium derived from an adjacent Cretaceous granite pluton travelled as both hydroxide and fluoride complexes within dominantly magmatic fluids. Emerald crystallized during cooling, after the magmatic fluids mixed with hydrothermal fluids that had scavenged chromium from the surrounding mafic schist. Property-scale exploration targets the permeable, highchromium mafic schists as potential hosts (rather than nearby chromium-rich, but impermeable, serpentinized ultramafic rocks). Soil geochemistry, drilling and prospecting are used to locate emerald mineralization. Based on the genetic model, further exploration in the Finlayson Lake region should focus on areas where permeable, high-chromium host rock (schist, rather than serpentinized ultramafic) is in close proximity to evolved felsic intrusive rocks.
