The True Blue aquamarine occurrence in the Quiet Lake area of southern Yukon is underlain by Paleozoic Cassiar Platform miogeoclinal clastic and carbonate rocks, a Mississippian syenite stock, Mississippian felsic metavolcanic rocks (Pelly Mountain Volcanic Belt), and a small carbonatite body associated with the syenitic intrusion. Beryl occurs in quartz veins and tension gashes, and is restricted to those that cut the syenite. Accessory minerals in the quartz veins include varying amounts of fluorite, siderite, calcite, allanite and ilmenite. Mineralization has been dated at 172 ± 5 Ma, using the Sm-Nd system on fluorite from several veins. Aquamarine discovered on the property is distinctive because of its deep blue colour and high Fe2+ concentration, up to 5.79 wt.% FeO. During the 2004 field season, diamond chainsaws were used to extract berylbearing vein material from the syenite.
