The Magnet showing is hosted by the Mississippian to Permian Nahlin ultramafic body, part of the Cache Creek Complex. The Nahlin body is 100 kilometres long and up to 8 kilometres wide and is the largest alpine-type ultramafic in the Canadian Cordillera. On the southwest it is faulted against Lower Jurassic sedimentary rocks (Inklin Formation, Laberge Group, and Upper Triassic Stuhini Group volcanic rocks) and on the northeast against Upper Paleozoic rocks of the Cache Creek Complex. This ultramafic body may consist of oceanic crustal ultramafic rocks consisting of: peridotite, dunite, pyroxenite, which is in general serpentinized, and locally includes pods of nephrite jade and small bodies of listwanite, rodingite, and talc. The rocks weather uniformly reddish brown and are generally devoid of vegetation.

The chrysotile occurrence is within pyroxenite which is slightly serpentinized and has phenocrysts of pyroxene up to 0.9 centimetre in diameter. The chrysotile occurs in both walls of a small stream canyon and is intermittently exposed for a distance of 35 metres along the canyon. Chrysotile occurs in varying amounts throughout this section in small discontinuous veinlets and boxwork structures which contain fibre generally less than 0.6 centimetre in length. A 0.3 metre section near the centre of the fibre zone, which is an intersection of two faults contains approximately 20 per cent fibre that averages 0.6 centimetre in length. The longest fibre noted was 1.3 centimetres long. Several of the chrysotile veins average 2.5 centimetres in width, but parting of the longest, strong fibres in these veins is common. Magnetite occurs along the fibre vein walls and at the parting planes within the vein.

Veins of serpentine occasionally containing discontinuous veins of chrysotile occur in the vicinity of the fibre zone. Less magnetite is present here. Calcite veinlets also occur infrequently in fractures in the pyroxenite.

Diorite dikes were noted to crosscut the ultramafic mass. A 1.5-metre-wide diorite dyke, located immediately west of the chrysotile occurrence, was noted to host traces of pyrrhotite.

The Magnet 2 and Magnet 4 claims were purchased by Centex Mines Ltd. in 1967 from the Orex Syndicate. The Nomad 1-18 claims were acquired that same year from principals of Centex Mines. During 1967 a magnetometer survey over the known fibre zone traced a low order magnetic anomaly approximately 425 metres north from the outcrop in the stream canyon. In 1969 two diamond drill holes totalling 92.65 metres were put down to test the downward extension of the fibre zone in the stream canyon. This drilling failed to confirm the downward extension of the known fibre zone.