Aurumin Ltd (ASX:AUN) has released a JORC-2012 mineral resource estimate of 803,000 tonnes at 2.51 g/t gold for 64,700 ounces in the inferred category at its Johnson Range Gold Project in Western Australia.
The estimate has been completed following extensive data validation and on-ground survey work at a cut-off grade of 1.0 g/t gold and within 100 metres of the natural ground surface.
Johnson Range Project is about 170 kilometres north of Southern Cross and 6 kilometres northwest of the Ramelius Resources Limited (ASX:RMS) owned historical Evanston Mine.
The project consists of 6 square kilometres of granted tenements and contains the shallowly mined Gwendolyn deposit at which the resource has been estimated.
Focused on ways to extract value
AUN managing director Brad Valiukas said: “Johnson Range is our third project and it is pleasing to have the mineral resource completed.
“We will now look at ways that we can extract value from the ounces we have in the ground and expect to be releasing first assays from the recently completed Mt Dimer drilling within the next week."
The Gwendolyn deposit is hosted in a moderately northwest dipping Banded Iron Formation (BIF)/Mafic/Ultramafic sequence within the Marda-Diemals Greenstone Belt.
Primary mineralisation is hosted by sheared quartz and breccias with lateritic (<5 metres depth) and supergene mineralisation also present in the near-surface.
A significant proportion of the mineralisation is confined within the transitional and oxide zones.
The mineral resource has a total strike length of 750 metres, is 80 metres wide and extends to around 150 metres depth based on current drilling.
Drilling techniques
Several drilling methods have been used throughout the project’s history including aircore, rotary air blast, reverse circulation and diamond drilling.
Drilling was completed in two main phases - the mid to late 1980s leading to a shallow open pit being mined and the early to mid-2010s (through Vector Resources Ltd) leading to a bulk sample mining phase.
Sampling and sub-sampling techniques
Multiple operators have been responsible for drilling and sampling at the project over its life and data collection has varied throughout this time.
Much work has gone into detailing sampling methodology through reference to historic documentation.
Assay and lithology data are consistent between the two main drilling phases and all data used for estimation is considered representative and equivalent.
Mining and metallurgical methods
Mining is assumed to be by open pit methods.
The maximum depth reported has been limited to 100 metres as a conceptual maximum open pit mining depth.
Open pit optimisations have not been completed and no modifying factors (mining dilution and recovery or processing recovery) have been applied to the reported mineral resource.
Eight PQ holes were historically drilled to determine the metallurgical parameters and showed very favourable results for the extraction of gold where the ore is oxidised (averaging 95.8% recovery), with a high gravity component.