The Nokomai valley is located within the pumpellyite/actinolite facies of the
Otago Schist, a regional scale metamorphic belt in Southern New Zealand. The
Otago Schist is dominated by psammitic and pelitic greyschist with more
subordinate greenschist, quartzite, marble, and ultramafics.
Mining in the Nokomai, began in the 1860s, with sluicing of terrace gravels in the lower valley.
Good gold is reported to have been won from unconformities within very weathered gravels
lower in the terrace sequences, and particularly from within channels which
dissect these older deposits. Gold was recovered from these terraces in the
main Nokomai Valley, and two major tributaries (Victoria Gully and Bullock Head
Creek). In the period 1885 - 1887 further gold was discovered in
basal gravels beneath the Nokomai flats when the Hunter brothers sank two
shafts and excavated a connecting drive to discover a lead 1.2 - 1.5 m
thick. The Golden Lion Sluicing Company began mining in 1896 using an hydraulic
elevator on the very 'tight' 1.8 - 2.4 m of basal gravels. This operation was
followed by the Nokomai Gold Sluicing Company whose average return grade was
>485 mglm3
until mining ceased in 1943 (Wopereis; 1988, 1989). A quartz vein, Commissioners Reef,
was worked for small production at some time during the 1920 -
1930 period, until fault termination of the vein ceased
production.