Abstract: In 1998, a new occurrence of emeralds was discovered in Finlayson Lake area, southeastern Yukon. Emeralds occur in the alteration selvages of quartz-tourmaline (-scheelite-muscovite-beryl) veins that cut biotite-chlorite metavolcanic schist in the metamorphic aureole around one of the area's largest bodies of mid-Cretaceous granite. In the area of the showing, the mafic schist, part of the widespread Upper Devonian Fire Lake unit, is meta-basalt of boninitic composition which overlies a thick, laterally tapering slab of variably serpentinized mafic and ultramafic meta-plutonic rocks. Using various geometric and geological criteria, this slab is inferred to be a sill, comagmatic with the Fire Lake unit, which intruded laterally from feeder dykes localized along a nearby synvolcanic fault.

Authors: Murphy, D.C., Fonseca, A., Lipovsky, P.S., Stuart, A., Groat, L. and Piercey, S.J.

Map Scale: 1 : 0

Citation: Murphy, D.C., Fonseca, A., Lipovsky, P.S., Stuart, A., Groat, L. and Piercey, S.J., 2003. What about those emeralds, eh? Geological setting of emeralds at Regal Ridge (SE Yukon) provides clues to their origin - and to other places to explore. Yukon Geological Survey, placemat series.

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