LEE A. GROAT and DAVID J. TURNER
Department of Earth and Ocean Sciences, University of British Columbia,
Vancouver, British Columbia V6T 1Z4
GEORGE R. ROSSMAN
Division of Geological and Planetary Sciences, California Institute of Technology,
Pasadena, California 91125-2500, U.S.A.
ABSTRACT
Dark blue
aquamarine was discovered in the Yukon Territory
in 2003. The crystals occur in a swarm
of quartz ± siderite ± fluorite ± allanite veins that fill tension gashes in a syenite
stock. Previous studies suggest a
metamorphic origin for the mineralizing fluid and local derivation of vein
constituents. The dark blue beryl
contains nearly 6.0 wt.% FeO and the colour is
thought to be due to intervalence charge-transfer between Fe2+ and
Fe3+ cations. Five stones weighing up to 0.82
carats were faceted in 2003, but these are heavily fractured and
included. However, many of the smaller
crystals discovered to date are transparent.