The Killingdal deposit was worked to a depth of 1,400 m with about 3 Mt with 1.7 % Cu, 5.5 % Zn, 0.4 % Pb and 45 % S being produced during more than 300 years of mining. The deposit consists of two ore bodies, the Main Orebody and the North Orebody, which are strongly elongated, with approximately lens-shaped cross sections and occur in the hinge of a regional-scale, isoclinal fold structure. The ore bodies are parallel for about 2,500 m of known length, dipping about 30o W.

At higher levels, the width of the Main Orebody between 40 and 80 m, and has a mean thickness of about 3.5 m, with a maximum at 10-12 m. The thickness of the North Orebody is considerably less than that of the Main Orebody and it has been exploited to a lesser extent. Pyrite is the dominant mineral, while sphalerite and chalcopyrite are subordinate phases. The principal gangue minerals are quartz and muscovite. Bands of pyrrhotite-rich ore up to a couple of centimetres in thickness are preferentially located near the hanging wall.