Combined geological ore "reserves" estimated by EEC (later CRA Exploration Pty Ltd) in the 1950's, for several mineralised "shoots/veins" were 375,000 tonnes @ 15% Zn and 2% Pb of mainly oxide material.
The leases in part contain and are surrounded by early to middle Proterozoic McArthur Basin rocks including Katherine River Group, Mt Rigg Group and Roper Group lithologies transected by the northwest trending Bulman Fault which is associated with the zinc and lead mineralisation at Bulman.
The combined "reserves" figure quoted by EEC was estimated following a programme of shaft sinking and bulk sample analysis at several localities inside and outside the current leases. Later drilling downgraded zinc and lead potential at depth due to a significant sill of dolerite occurring at shallow to moderate depth beneath the known mineralisation. However, significant near surface zinc and lead oxide ore remains, but largely untested with respect to modern systematic sampling and drilling practices.
A literature review of available open file exploration data from the 1950's to the present day has highlighted the Bulman Leases and five nearby zinc and lead occurrences as having potential for at least one million tonnes of at-surface and near-surface exploitable oxide and sulphide ore at greater than 10% combined zinc and lead.
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