The showing is located near sea level on Alder Island, 800 metres off the north end of Burnaby Island. It was staked in 1922 as two recorded claims.

Alder Island is underlain by complex geology, including folded limestone and argillite of the Jurassic to Triassic Kunga Group, Middle Jurassic Yakoun Group volcanics, Lower Cretaceous Longarm Formation sandstones, Tertiary Masset Formation basalts and granitoid dikes related to the Middle to Late Jurassic Burnaby Island Plutonic Suite.

An intense fault-mylonite zone extends the entire east side of the island. The mylonite is composed of shattered country rock, which is mainly Yakoun volcanics in the south and skarn, variably developed in Longarm sandstones in the north. A silicified, chilled contact occurs between a hornblende monzonite and sheared greenstones to the east.

The massive to poorly bedded garnet-actinolite-diopside-zoisite skarn is interbedded with baked cherty siltstone and layered carbonate. Massive pyrrhotite pods with accessory chalcopyrite, molybdenite and magnetite occur along the skarn and fault-mylonite zones. Allemonite is associated with calcite veins and the pyrrhotite mineralization, which is sometimes nickeliferous.