BMEX - Broken Hill and Mount Isa Zn-Pb-Ag Projects
In mid 2018 Altius Australia sold its 100% interest in 3 granted Exploration licences over Broken Hill district (Figure 1) and 4 similar licenses on the Mount Isa district to a private Australian explorer, BMEX for 3.5 million shares (500,000 shares per license) and retention of a 1% gross sales royalty covering the licenses. As part of the arrangement BMEX is required to go public within 18 months and to spend a minimum of $500k in expenditures advancing the claims. At the end of June 2019, Altius ownership has increased to 8 million shares, having received additional payments in shares. BMeX is preparing for an ASX listing.
The Broken Hill properties cover an extensive area (347 km2) of largely untested prospective Broken Hill Group stratigraphy under cover in the western part of the district.
The Broken Hill deposit is the largest single sediment-hosted Zn-Pb-Ag deposit in the world and has been mined continuously since the late 1800’s, and the region continues to support three mining operations. The project area lies under cover to the west of the outcropping area of the Broken Hill block. Whilst there has been previous exploration, the large area under claim has only hosted a total of 18 drillholes which intersected basement. These drillholes have largely confirmed the presence of prospective Broken Hill Group rocks.
License EL8485 - Reinterpretation of magnetics and gravity (Figure 2) has allowed the identification of a likely synsedimentary growth fault which marks a transition from relatively thin Broken Hill Group to a relatively thick and polydeformed sequence in the main part of the tenement. Reprocessing of gravity data has allowed the recognition of a gravity ridge which crossed this structure and may be related to underlying faults and/or lithological boundaries. The small amount of drilling in the area has confirmed the presence of Broken Hill group rocks, though the main target area has not yet been tested
License EL8569 - Magnetic interpretation on this area has allowed the recognition of a structural inlier of Broken Hill Group within stratigraphically lower and more magnetic rocks. Within this package there are a number of strike-discontinuous magnetic anomalies which may represent the BIFs often encountered in association with Broken Hill lode rocks. The overall geological setting in this area is somewhat analogous to that seen at Cannington in Queensland, another BHT deposit.
License EL8484 - In this area, subcrops of Broken Hill group lie under shallow cover. Previous exploration has been strongly focused on geophysics, and there is potential to trial geochemical approaches which may identify systems not tested in previous programs.
The Thorntonia Project (EPM26518, EPM26514) targets Isa/Century style zinc-lead-silver mineralisation. The area is under shallow to moderate cover interpreted to be mainly less than 100m. EPM26514 boasts an untested magnetic anomaly identified by CRAE in the 1990’s which remains untested due to ‘difficult drilling conditions’
The Min Min Project (EPM26516) targets Cannington-style Silver-Lead-Zinc mineralisation. The area is under 300 + metres of cover, with the interpreted basement lithology being Norna Quartzite of the Soldier’s Cap group. The structural setting is interpreted to be at the intersection of CS2 and CS3 transfer faults.
The Surprise Project (EPM26517) targets Isa/Century style zinc-lead-silver mineralisation. Cover interpreted between 100 and 200m. Target stratigraphy intersected by previous explorers is confirmed in the Altius ground. The tenement application is in 2 parts straddling the Bluebush Zn Project held by Pursuit Minerals.
Broken Hill’s silver endowment also places it amongst some of the greatest silver districts in the world, though little attention has been paid to the high-grade silver targets in the district. The project hosts a large number of silver occurrences and historical mines which were exploited in the late 1800’s, the most important of which was the Umberumberka mine (within EL8485), which produced 43,000 tonnes at an average grade of 10% Pb and 796 g/t Ag, including high grade samples of up to 66,650 g/t Ag hosted in quartz-siderite veins of up to 4 metres width. Historical reports and recent drilling show that mineralization remains open at depth, and the retrograde shear zones which host silver mineralization are extensive in the area under claim.
Thackaringa-type deposits occur in clusters, with some of the largest clusters occurring in the Broken Hill Block North area. The deposits form an arcuate discontinuous belt of clusters extending north-easterly along the Apollyon Valley schist zone and its forks, as well as in the Silvertone area (EL8484) where the Altius ground is located, and in the Consols mine near Broken Hill. Retrograde Schist zones control the distribution of these belts.
Joe Potter, RPGeo., is the qualified person responsible for the technical data presented herein.