In December 1969, it was decided that the mining at Mount Gunson, scheduled to start in late April 1970, would commence with the development of the East Lagoon orebody. This orebody was selected because it appeared to contain the highest grade sulphide mineralisation, even though the potential tonnage of ore appeared to be not as great as in other deposits nearby. A deciding factor in this choice was that previous drilling had suggested a better continuity of mineralisation at East Lagoon compared to the other deposits. Results of the three East Lagoon orebody definition percussion and diamond drilling programmes completed to date were compiled and interpreted. In consequence the ore reserves at East Lagoon are presently given as : measured ore - 203,000 short tons of 1.43% Cu; indicated ore - 46,000 short tons of 1.26% Cu; inferred ore - 26,000 short tons of 1.05% Cu. Continuity of ore grade and thickness for the central part of the orebody has been substantiated by the latest infill drilling, with significant copper mineralisation encountered in 40 of 60 percussion holes put down on a 100 foot x 100 foot grid, but the lateral limits of mineralisation have not been fully determined, except perhaps in the south. Further definition drilling is recommended to fully quantify this orebody before mining of it commences.