Herbert North Upper Triassic shaly sediments are overlain by rhyolitic to andesitic pyroclastics in a saddle south of Mount Henry Clay. This sequence is overlain by pillowed basalts. Mineralized volcaniclastics form a large, white, rusty weathering gossan which is a minimum of 35 metres thick. A 10 metre thick bed of light green andesitic tuff is stained on the surface with small patches of mala- chite, and contains disseminated pyrite and chalcopyrite and a pro- fusion of pyritic microfractures. A grab sample assayed 1.36 per cent copper, 1.13 grams per tonne gold, and 13.7 grams per tonne silver with trace lead, zinc, and cobalt. An outcrop of malachite- stained talc schist with no visible sulphides assayed 3.11 per cent zinc and 8.57 grams per tonne silver (Assessment Report 12629). Other mineralization consists of galena in quartz veinlets within chert.

The target horizon at the Low Herbert (114P 064) is strati- graphically identical to the target horizon at Mount Henry Clay (Herbert North). Both are composed of a volcaniclastic-sedimentary unit which is overlain by a pillow basalt and underlain by a sequence of flow and agglomerate andesites. The more acidic volcanic- sedimentary unit is up to 150 metres thick.