Narracoota

The Narracoota project comprises a 111km² granted tenement (E52/1496) located 70km north of Meekatharra, WA and 75km southwest of the significant DeGrussa copper-gold discovery.

Sandfire Resources’ (ASX Code: SFR) DeGrussa copper-gold discovery appears to be a volcanogenic massive sulphide (VMS) deposit and is hosted within rocks of the Narracoota Volcanics.  Richmond Mining’s Narracoota project contains extensive widths of Narracoota Volcanics that are interpreted to occur in at least three structural repetitions, providing a target zone of approximately 20km in length.

Within the strike extension of the main structural repetition lays the Bilyuin magnetic anomaly.  This is a large magnetic feature (approximately 5km long and averages 1 km in width) associated with a volcanic breccia complex outlined in the southern part of the tenement from geophysical data and limited historic drilling.

The Bilyuin magnetic anomaly, coincident with a prominent regional gravity high, is interpreted to be an ancient volcanic centre and could be a possible heat source for the remobilisation of metals, if any are present in the area.  Consequently the breccia could be the ideal host for possible VMS style Cu-Au or Cu-Zn-Pb-Au-Ag systems.

Richmond’s prior exploration focus at Narracoota has been on delineating structurally controlled gold mineralisation.  The company drilled 20 aircore holes on widely spaced traverse lines into the Bilyuin anomaly as a geochemical test for gold in the weathered rocks beneath the extensive alluvial cover across a number of structural features associated with the breccia and fault zone within the anomaly.

No significant gold results were returned, however, the best intercept was 2m @ 0.08 g/t gold from 80-82 metres in a weakly foliated, weakly weathered basalt; 100 – 200 metres south of an interpreted NW trending structure.  The aircore drilling also highlighted that much of the historic drilling over the anomaly was probably ineffective as a result of misinterpretation of alluvial clays as weathered bedrock.

The most significant discovery made over recent years in the vicinity of the Narracoota project is the DeGrussa copper-gold discovery at Doolgunna.

The DeGrussa prospect was being explored for gold mineralisation, which was reported as being associated with a pyritic shear hosted in strongly weathered and oxidised saprolitic basalt.  In follow up testing for extensions of the gold zone at DeGrussa it was reported that drilling had intersected significant intervals of high grade gold and copper mineralisation within and beneath the previously delineated oxide gold zone.

Similar DeGrussa style mineralised structures could exist on E52/1496 and have easily been missed by the wide spaced drilling, as the surface projection of the >0.1 g/t gold mineralised shear zone at DeGrussa is shown as being only 40m wide.

Richmond’s exploration effort will now focus on the potential for the Narracoota Volcanics in E52/1496 to host VMS copper-gold mineralisation.

Also within the tenement and bounding the Narracoota Volcanics are sediments that are potentially important in the VMS exploration model, as they provide additional depositional sites for mineralising fluids.

Although the Narracoota project has had an active exploration history, previous explorers have been hampered because much of the area is covered by transported sediments that overlie a thick leached weathering profile.

Four known prospects and mines (Durack Well, Wembley, Mikhaburra and Cashman) lie very close to the Narracoota tenement boundaries.

Approximately 1km from the southern boundary is the old Cashman copper mine that produced 7t of copper ore grading 16.5% copper.  Immediately surrounding the Cashman deposit is a number of small mineral occurrences and deposits, which contain copper and copper-gold.

The Mikhaburra gold deposit, also known as Holdens Find, is also located approximately 1km from the southern boundary and is hosted in volcanic rocks of the Narracoota Formation.  Total recorded production of the Mikhaburra mine was about 226 kilograms of gold and mineralisation is associated with a system of auriferous quartz veins emplaced along a shear zone.

Richmond’s Narracoota project has the right rock types that host nearby mineralisation and presents a significant copper-gold target along strike from the DeGrussa discovery.

The initial exploration for VMS copper-gold mineralisation in the Narracoota Volcanics within E52/1496 will rely on geophysics techniques that can detect this style of mineralisation beneath the thick transported cover and deeply weathered regolith profile.  An airborne electromagnetic survey is currently being planned for the tenement.