Lincoln Minerals (ASX: LML) has kicked off a significant re-assay program at its Minbrie copper-lead-zinc project near Cowell in South Australia as the company chases what it believes could be a major new base metal discovery.
Lincoln will re-test 69 of 266 diamond holes drilled in 2011 by resources company Centrex Metals in its hunt for magnetite iron. The drill holes were never fully assayed for key base metals.
The move follows an initial re-evaluation of historical drill data from Centrex’s campaign.
Lincoln discovered that only about 40 of the holes hit a footwall sequence that shows strong signs of metasomatic and hydrothermal mineralisation. Of those drilled to test the base contact with the banded iron, only 16 per cent were assayed for base metals.
Under a minerals sharing agreement at the time, Centrex controlled the rights to any iron discoveries while Lincoln retained ownership of any other minerals.
Centrex later handed the project’s keys and core shed to Dragon Investments, a subsidiary of Hoa Phat, Vietnam’s biggest steel manufacturer, while Lincoln’s existing agreement remained intact.
One particular result unearthed from the files that got tongues wagging and convinced Lincoln to take a second look was a hit of 12m running at 1.4 per cent copper, 12.4 per cent lead, 2.0 per cent zinc and 13 grams per tonne (g/t) silver from 139m depth.
A 1m section within the same intercept graded as high as 4.8 per cent copper, 31 per cent lead, 3.14 per cent zinc and 36g/t silver from 145 metres depth.
Given Lincoln has so much untested core at its disposal, it is taking a targeted approach to unlocking the full potential of the project.
Unassayed intervals near known mineralised zones will undergo re-assay for footwall sequence analysis as a priority. This includes 38 drill holes and 473.8m of previously untested core that intersected key mineralised layers.
The assay lab with then move onto 25 holes that intercepted massive sulphides. Of nearly 200m of mineralised core, 69 metres remain unassayed and need to be re-examined.
Geotechnical holes targeting base metal-rich stratigraphy will also be re-assayed to complete a comprehensive assessment of the area’s high-potential zones.
Centrex built an entire geological model across the area as part of its original drilling campaign, which cost more than an eye-popping $30 million to complete.
Lincoln is now working on a theory that a potentially rich, untapped resource may sit in the footwall of the banded iron contact.
The company is re-processing the model 300 metres east of Centrex’s efforts to give it a more detailed interpretation of the geology.
Access to Centrex’s core samples and some of the assay pulps has gifted Lincoln the opportunity to initiate a cost-effective re-assay strategy.
Management says the existing data is so comprehensive that Lincoln may be able to unlock a discovery without the need for immediate redrilling.
Minbrie is in the Gawler Craton, which is one of Australia’s premier mining regions and home to world-class deposits such as BHP’s Olympic Dam, Prominent Hill, Hillside and Carrapateena.
I feel this site represents the most exciting exploration opportunity in South Australia. Our goal is not only to provide evidence of a major base metal discovery but also allow Lincoln to develop and undertake an exploration program.
Lincoln Minerals CEO Jonathon Trewartha
With punters likely focused on the outcome of a program designed to unlock hidden value in the historic drill core at Minbrie - expected by May - Lincoln will have to be ready to make some quick decisions on further exploration plans and resource delineation drilling.
If the re-assay results confirm extensive mineralisation, Minbrie could emerge as another major base metal discovery in the fabled Gawler Craton.
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