The Harvey Lake Beryl occurrence is located 1.9 kilometres east of the eastern shore of Harvey Lake, approximately 25 kilometres south of the confluence of the Dease and Blue rivers, 130 kilometres northeast of the community of Dease Lake.
The area is underlain by rocks of the Upper Proterozoic Ingenika Group, Lower Cambrian Atan Group, and Ordovician to Lower Devonian Sandpile Group. The Ingenika Group consists mostly of medium to high grade metamorphic grade schists, quartzites, marble and minor orthogneiss. The overlying Atan Group consists mainly of quartzite. The Ketchika Group is composed mainly of chloritic phyllite and schists and the Sandpile Group of dolostones and dolomitic limestones. These have been intruded by igneous rocks consisting of mid-Cretaceous and Eocene age granitic dikes, pegmatite, ultamafic and mafic rocks. Granitic dikes occur in the Ingenika Group. Ultramafic and mafic rocks are exposed as undeformed bodies in the Ingenika and Ketchika groups and as mylonitized to undeformed bodies in the mylonite zones.
Locally, an ultramafic/mafic zone occurs and is divided into two units. The first is a coarse grained, phenocrystalline, biotite-bearing ultramafic unit characterized by a knobby weathered appearance and dark brown or rusty colour of phenocrysts. The second unit is medium grained and equigranular mafic rock. The contact between these units is commonly separated by granitic and pegmatitc dikes and/or sills with lepidoblastic texture and foliation.
In 1997, one day of prospecting was performed in the Harvey Lake area by B.S. Wilson and G. Simandl. In 2005, sampling of this zone found industrial to gem quality beryl crystals occurring in coarse grained granite dikes and pegmatites. The crystals are described as being pale blue in colour, translucent and vitreous lustre. Rare crystals of beryl are colourless and transparent. Individual beryl crystals vary in size from 0.1 to 5.0 centimetres in length and from 0.1 to 3.0 centimetres in width. In some locations, about 5 per cent of the granite/pegmatite is composed of beryl crystals. The normal concentration of beryl observed in granite/pegmatite was less than 0.1 per cent (Assessment Report 28029).
