The immediate Heffley Lake area is extensively covered with superficial glacio-fluvial deposits and is estimated to have less than 1 per cent rock exposure. Stratified rocks mainly comprise steeply dipping, northwest striking argillites and calcareous siltstones with lesser andesitic ash and lapilli tuff and some limestone belonging to the Devonian to Permian Harper Ranch and/or Upper Triassic Nicola groups. These rocks were intruded by the possible Late Triassic to Early Jurassic mafic-ultramafic Heffley Creek pluton and then folded and overprinted by lower to sub-greenschist metamorphism producing slaty and phyllitic fabrics. Bleached marbles and calcsilicate-rich metasediments are developed where hydrothermal or thermal alteration has occurred.
South of Heffley Lake are units of blue-grey crinoidal limestone and black argillite while north of the lake are coarsely clastic to conglomeratic limestone in the vicinity of the Heff skarn (092INE096) which lack crinoids and the argillites are less organic-rich. This and other lithological differences suggest that these rocks may be separated into northern and southern packages; these are tentatively believed to represent the Nicola and Harper Ranch groups respectively. The northwest trending contact between these packages is thought to pass under the Heffley lakes and continue southeastwards along Armour Creek. This original stratigraphic contact has been intruded by the Heffley Creek pluton and has subsequently been the locus of brittle movement along the Armour Creek fault (Fieldwork 1999).
Disseminated cumulate magnetite is common throughout the main Heffley Creek pluton but locally some pyrite +/- chalcopyrite +/- secondary copper oxides are also seen. Many of these sulphide-rich zones are characterized by silicification and plagioclase veining and they appear to be fault related. At the Hawk showing, quartz veins up to 3 centimetres wide and 5 metres long occur in silicified diorite of the Heffley Creek pluton in fault contact with marble and argillite. The quartz varies between clear to limonitic crystalline quartz to fine banded milky veins. Scattered euhedral galena and pyrite crystals occur; vugs are common. Native gold particles up to 1 millimetre in size occur in limonite and near black sooty material in vugs. A sample without visible gold assayed 0.99 gram per tonne (Assessment Report 17147). Malachite staining, pyrite and magnetite are also evident.
Pyroxene +/- garnet skarn has also developed in marble and contains disseminated and veinlet pyrite and pyrrhotite. A limonitic sulphide-rich vein in the skarn analysed 1.37 grams per tonne gold. About 100 metres west of the Hawk showing, quartz veins also occur in silicified andesitic rock. This material was blasted open and revealed two near-vertical massive sulphide veins. The first vein, up to 0.8 metre wide, consists of pyrrhotite, pyrite and chalcopyrite; a grab sample assayed 0.55 per cent copper. The second vein is up to 10 centimetres wide, is sheared and occurs two metres east of the first vein. Grab samples of the wallrock assayed 0.47 gram per tonne gold (Assessment Report 17147).
During the spring of 1987, C. Marlow and W. Hall discovered native gold in a thin quartz vein and noted skarn-like rocks nearby. They entered into a grubstake agreement with M. Roed of Foxview Management Limited who engaged a consultant (M. Murrell) to study the showing. As a result, the Hawk 1-8 claims were staked and an exploration program was undertaken. The claims were optioned to Redbird Gold Corp. and in 1987-88 conducted geologic mapping, rock and soil sampling, photogeology and a magnetometer survey; minor blasting was also carried out on some showings.
