The Sunny magnesite showing is 3.5 kilometres northwest of the confluence of Blue Creek with the Yalakom River. The showing is within quartz-carbonate altered serpentinite (listwanite) of the Permian and older Shulaps Ultramafic Complex.

The alteration zone is adjacent to (and southwest of) the Yalakom fault and is 30 to 100 metres wide and several kilometres long. Crystalline magnesite and quartz form banded veins and comb-textured intergrowths indicative of high level, low temperature hydrothermal alteration. Enclosing rocks vary from serpentinite to quartz carbonate mariposite rock (listwanite). The dimension of the most significant crystalline magnesite "vein" is 915 by 3.7 metres; the attitude of this "vein" is 130 degrees/vertical. Samples collected from this vein contain between 32 and 42.8 per cent MgO.

The style of alteration and textures of mineral assemblages suggests that hydrothermal alteration was rather intense and high level, probably similar to an epithermal environment. The Yalakom Fault undoubtedly played an important role in helping to focus hydrothermal fluids.