CuFe Ltd (ASX:CUF) has upgraded its existing Tennant Creek resources at the Orlando, Gecko and Goanna deposits following an independent review.
The company engaged Ian Glacken from Snowden Optiro Consultants to conduct a review of the stated 2004 resources and complete the necessary additional requirements to allow reporting under JORC 2012 requirements.
The original resource estimates were generated by Optiro Pty Ltd between 2011 and 2013.
Review conducted
Optiro was provided with all necessary information to enable interpretation including a fully validated drill hole database and wireframes of the weathering surfaces.
The database contained copper grades from 4,217 samples and gold grades from 3,063 samples with drill lines spaced between 10 and 20 metres and hole spacing between 20 and 30 metres.
Density data was estimated from 1,953 measurements taken from 33 diamond drill holes and separated into weathering zones and mineralised or unmineralised material. Interpretation used a 0.5% copper cutoff and a 0.5 g/t gold cutoff.
Gold and copper modelled independently
There was no correlation between gold and copper in the statistical analysis so they were modelled independently although there was some overlap in places. Estimation was controlled by eight separate mineralised domains with four for copper and four for gold all constrained with hard boundaries (wireframes).
Interpolation was carried out using ordinary kriging guided by variograms calculated for each domain and three pass searches were used according to the variogram models.
Resource classified based on confidence in grade continuity
The mineral resource was classified into indicated or inferred based on the confidence in geological and grade continuity using drilling density, modelled grade continuity and kriging efficiency.
The mineral resource was reported using a gold equivalent cutoff of 1.0g/t using US$1,363 per ounce for gold and US$3.31 per pound for total copper after depletion for previous open pit mining and underground workings.
The Gecko resource was estimated in July 2011.
All deposits were based on the assumption of underground mining with some possibility for a cutback to the existing pit in the Orlando deposit prior to going underground.
Processing was assumed to be via a gravity gold circuit on the front end with the possible addition of acid leach for oxide copper extraction followed by floatation of sulphides producing a copper concentrate for smelting and a gold tail for carbon-in-leach (CIL) and elution to produce ore on site.
Next steps
There has been no additional exploration, deposit definition or estimation conducted since the date these mineral resources were reported.
CuFe is currently in the process of conducting an infill drilling program including geotechnical and metallurgical drilling to support an updated estimation of the Orlando deposit for use in a possible expansion of the existing Orlando open cut mine.