When skulking around the back blocks of the ASX last week looking for some decent drill hits to pontificate about, it was hard not to notice Chilwa Minerals’ managing director Cadell Buss’ musings about the total heavy minerals (THM) at the company’s Mposa project in Malawi.
Buss pointed out that the THM found in a recent drill campaign came in “thicker and richer” layers than anticipated – much like we here at Bulls N’ Bears like our icecream. Delicious!
And a closer inspection of Chilwa’s results show the company is having a fair lick at it, indeed.
So, let’s dive in.
Chilwa Minerals
Mposa project – Malawi
Hit: 13m at 10.5 per cent total heavy minerals (THM)
Chilwa’s recent drilling, aimed at increasing its confidence in the current resource estimate at its Mposa sands project in Malawi, jagged 13m at 10.5 THM from surface – including 4m going 21.9 per cent – while a separate hole cored 1m going 45 per cent.
While the 13m intercept is the best to date on a metres-by-grade basis, the best grade in the company’s early going is 36.6 per cent THM in a 3m interval.
The top 10 holes in the latest program gave up intercepts ranging between 6m and 13m thick, with grades ranging from 10.5 THM to 26.3 per cent. The results are the vanguard assays from the first 50 vertical holes for 570m put in using sonic drilling in a planned program of 17,000m at the project.
Chilwa kicked off its maiden drilling at Mposa mid-last year in a bid to expand and improve its confidence in the existing 19.4 million-tonne Mposa Main inferred resource on the western margins of Lake Chilwa.
Management says the intercepts in the sonic holes drilled so far are typically thicker than the average of 5.5m from the historic drilling upon which the Mposa Main inferred resource is based. The drilling has intersected mineralised thicknesses in the range of 6m to 13m, with an average of 5.75m in the 50 holes already drilled.
Those numbers are attributed to better sample recovery using the sonic technology, which can obtain a relatively undisturbed core sample through many types of weakly-consolidated formations.
The company says the new drilling method has lifted sample recoveries to 95 per cent, contrasting significantly with the previous rates that averaged less than 70 per cent. And of greater significance is that the recent analyses commonly show higher grades than those from previous drilling used in the original mineral resource model.
Chilwa’s approach highlights a classic example of the worthiness of undertaking orientation programs to establish optimal drilling, sampling and analytical methods. Once the program is completed, the combined improvements – if sustained – could support a material resource upgrade in tonnes and grade.
Given the overall scale of the total estimated resource in all categories in the company’s string of 10 deposits arrayed around the 60km of the Lake Chilwa shoreline – amounting to 61.6 million tonnes at 3.9 per cent THM – the potential rewards from even a few per cent improvement in tonnes or grade, or both, can make a material difference to the project’s bottom line.
Magnetic Resources
Laverton project – Western Australia
Hit: 23m at 6.3g/t gold from 317m
During Magnetic’s recent bid to further infill the existing drilling pattern in its promising Lady Julie North 4 Main Zone (LJN4) at its Laverton project – and to probe further down-dip with successive step-back holes – a diamond drillhole scored a best intercept of 23m at 6.29g/t gold from 317m.
That hit includes 6m at 12.23g/t gold from 319m, which in turn features 13m at 5.08g/t gold from 327m.
The continuity of the LJN4 gold mineralisation has now been proven to a depth on that section of about 400m vertically below surface by that “best hit” hole, in tandem with a deeper diamond hole that bored through 25m going 3.86g/t gold from 386m including 12m running 4.5g/t from 392m about 112m further down-dip.
In addition to another 10 holes on the same section, they form a fence of 12 progressive step-backs of mostly reverse-circulation (RC) holes put in to test for down-dip extensions of the LJN4 northern area mineralisation where a high-grade gold zone dips at about 45 degrees to the east to about 400m.
A new 650m step-back hole is now planned to test for a further 130m extension down-dip and going by previous intercepts and grades in the system, the odds are that the proposed hole will hit paydirt, too.
Systematic drilling on adjacent sections along the strike of the mineralisation shows much of it to be of similar thickness and grades when compared to the previously-described section.
The LJN4 zone exhibits continuous gold mineralisation along its entire 750m strike at surface. Most of it is contained within a prefeasibility pit outline, but the core high-grade zone within the deepest part of pit remains open to depth below the pit floor.
The company is planning a further five holes for 2300m of drilling with an eye to fleshing out the persistent high-grade mineralisation further down-dip.
Magnetic says Laverton’s overall resource has lifted by 7.7 per cent to 24.9 million tonnes at a grade of 1.66g/t gold for 1.33 million ounces of gold, while the local LJN4 resource has hiked by 11 per cent to 948,200 ounces of gold.
Management says, as seems to be the case with other world-class multi-million-ounce deposits in the Laverton region, that it has already identified eight stacked lodes in the central part of LJN4 and has recently completed a 717m hole below the stacked lodes, with results awaited.
Due to the promising enlargement of its northern zone, the company says it has kicked off a new round of resource upgrade assessment.
West African Resources
M1 South target – Burkina Faso
Hit: 10.5m at 15.25g/t gold from 56m
West African’s recent diamond-core underground infill drilling was rewarded with a best hit of 10.5m going 15.25g/t gold in the M1 South target’s northern shoots of the company’s Sanbrado gold operations in Burkino Faso in Northern Africa.
That best intersection also included 1m at 110.33g/t gold, while other strong hits include 6m at 25.76g/t, 3m at 43.06g/t, 14.5m at 7.51g/t and 9.5m at 9.58g/t.
The results include a veritable treasure trove of hits with grades that most people would be glad to see in their panning dishes, ranging from 30g/t gold to 60g/t in intercepts from 3m to 14.5m. The suite confirms development ore for the company for the second half of the year, with development of the M1 South northern shoots slated to kick off in this year’s third quarter.
The M1 South drilling aims to convert up to 400,000 ounces of gold from inferred to indicated mineral resources and it is expected the outcome of that aspiration will emerge in the third quarter.
To meet that requirement, the M5 South exploration drive has also been launched, with drilling planned for the closing days of the last quarter of the year. It will extend about 800m from the existing underground at M1 South and will provide collar positions for up to 15,000m of resource extension drilling.
The goal is to extend the resource at depth by up to 300m and it has the potential to double the life of the potential M5 South underground.
Management says it has put 43 holes into the northern shoots between 1920RL and 1800m RL, which has produced sufficient data to enable mining to go ahead. The block model is being updated so mine designing and scheduling can take place.
Is your ASX-listed company doing something interesting? Contact: matt.birney@businessnews.com.au
