The Arm occurrence is reportedly located on the north west slopes of a hill located immediately south west of the mouth of the Phillips River and approximately 3.1 kilometres northwest of Hewitt Point.

The area is underlain by a persistent band, greater than 12 kilometres long, of stratified metavolcanic and metasedimentary rocks of the Upper Triassic Quatsino and Karmutsen formations (Vancouver Group). The band trends north- west and separates Jurassic to Cretaceous Coast Plutonic Complex rock of two different compositions, diorite and granodiorite.

A showing of chalcopyrite is reported on a mineral occurrence plot in Geological Survey of Canada Open File 480.

In 1983, Bute Joint Venture completed a program of rock and soil sampling, geological mapping and ground magnetic and electromagnetic surveys on the area as the Koop and Strider claim groups. The area was prospected as the Cordero property in 1991 and 1992 by Ripple Creek Resources. During 1997 through 2000, Thurlow Resources conducted exploration programs on the area, renamed the DM and Picton properties, on the HY, LO, and FILL 2-19 claims. The programs consisted of soil sampling, rock sampling, and geological mapping. In 2008, Cuda Capital completed a 561.4 line-kilometre airborne magnetic survey on the area.