Tertiary Minerals (LSE:TYM) announced plans to drill up to 1,000 metres of diamond core at its Target A1 prospect within the Mushima North project in Zambia, which will be its first diamond drilling campaign on the site.
The programme of up to four angled holes, each 200 to 250 metres long, will test for mineralisation to a vertical depth of about 200 metres, considerably deeper than the current exploration target of roughly 95 metres, and the recent Phase 4 reverse-circulation programme's maximum depth of 125 metres.
Target A1 already carries an exploration target of 15 to 30 million tonnes (at 40 to 60 grammes per tonne silver equivalent) implying up to about 58 million ounces of contained silver equivalent. The company is working toward a maiden JORC Mineral Resource Estimate by the end of the year.
The AIM-listed explorer, which focuses on silver-lead-zinc and related base and precious metal targets in Zambia and Nevada, said the new drilling aims to establish whether near-surface oxide mineralisation transitions into an underlying primary sulphide deposit, a question the Phase 4 programme left untested.
That Phase 4 campaign delivered the project's best intersections to date, including 121 metres at 56 grammes per tonne silver, 0.26% copper and 0.37% zinc (78 g/t silver equivalent) from 4 metres downhole in hole 26TMNRC-053, which ended in mineralisation, and 82 metres at 89 g/t silver, 0.20% copper and 0.38% zinc (107 g/t silver equivalent) from 8 metres in hole 26TMNRC-066, also ending in mineralisation.
Richard Belcher, Tertiary's managing director, said the programme "will test for the continuation of mineralisation below the Discovery Zone, and in particular for the potential of underlying primary sulphides."
Belcher highlighted that other planned work includes expanding the analytical suite for critical metals including rare earth elements, further metallurgical testwork, and environmental and community baseline surveys, calling it a push toward "a very strong finish to this year's Zambian field season."
Drilling is slated to start once funding is secured following a general meeting on 28 October, with field preparation due to begin within days; the programme is estimated to take about four weeks.
The meeting will ask shareholders to approve the £1 million placing conditionally raised in September through SP Angel Corporate Finance, a placing of 1.67 billion new shares at 0.06p that represented a 14% discount to the five-day volume-weighted average price, with proceeds earmarked for deeper drilling beneath the oxide zone, critical-minerals assaying, expanded metallurgical testwork and environmental surveys.
The samples will be screened on site with a portable X-ray fluorescence analyser for copper and zinc, with selected intervals sent to a certified laboratory for a wider element suite including silver, copper, zinc, cobalt, bismuth, antimony, gallium and rare earths; first certified results are expected six to eight weeks after the initial batch is submitted.
Mushima North sits in Zambia's Iron-Oxide-Copper-Gold belt, about 28km from the historic Kalengwa copper-silver mine, which is currently under redevelopment. Tertiary holds the project through its 90%-owned subsidiary Copernicus Minerals, with local partner Mwashia Resources holding the remaining 10%.