In this week’s edition of Bulls N’ Bears Big Hits, we examine some of the more notable drill intersections revealed on the ASX, including Solstice Minerals’ interesting runs of low-level composite gold results that are being re-assayed in a bid to highlight potential new exploration targets.
We also take a close look at other interesting drill hits from last week as reported by Peel Mining from its Cobar South projects in New South Wales, Sun Silver in Nevada and Cauldron Energy from its operations in Western Australia’s coastal North West region.
So, let’s dive in.
Yarrie Project – Eastern Goldfields, WA
Hit: 10m at 3.61 grams per tonne gold from 41m
Solstice jagged this promising shallow hit that includes 5m at 6.48g/t gold in a composite sample from one of 17 reconnaissance air-core (AC) holes drilled recently for a total of 1464m at its Bunjarra prospect.
Since launching its maiden 70-hole, broad-spaced AC assault on the westernmost area in the Bunjarra tenement group in September last year, the latest program is the company’s third AC campaign and the second follow-up on the ground.
In October last year, the company reported composite sample assay results that included an intriguing teaser from its second hole, which intersected 10m at 0.18g/t gold from 25m, just above the transition zone between weathered and fresh rock.
Interestingly, the adjacent first hole in the program, just 200m to the east of the second, also produced a composite sniff of 5m at 0.28g/t gold from 69m from the same transition zone, but deeper.
Management formed the view that both hits could represent gold anomalism at or near end-of-hole (EOH) drill refusal, possibly related to a combination of downward leaching and accumulation of gold in the transition zone between weathered and fresh rock. The 10m teaser was subsequently re-split to its component intervals and re-assayed, delivering an infinitely more interesting 2m at 1.85g/t gold.
A second round of drilling in May this year then saw the company drill a further 18 AC holes at 100m spacing for a total of 1470m to test the south-eastern portions of the Bunjarra licence area. It focused on possible northerly strike extensions of a structural corridor evident in aeromagnetic data in third-party ground to the south, which hosts fresh-rock gold mineralisation.
Composite sample results from the May drilling returned gold anomalism including a near-EOH result of 5m at 0.87g/t from 77m, about 850m north of the headline intercept and in an identical structural situation on the same interpreted arcuate magnetic trend. That composite was also split and re-assayed, yielding 1m at 4.49g/t gold.
The stronger May results bolstered Solstice’s view that EOH gold anomalism in multiple locations at Bunjarra could indicate the potential for a regional structural gold target hidden below shallow transported soil cover.
The geology at the site is covered by a blanket of shallow transported alluvial material that has limited the effectiveness of previous exploration.
Both the original hole and the hole featuring the headline hit bore through the same mineralisation within mere metres of each other. The original vertical hole runs to EOH at 40m depth, terminating about 10m above the later headline hit, which runs from 41m to 51m downhole, ending at 56m.
At this stage, the company’s inferred “bedrock” potential is screaming out to be tested and early future work is also likely to explore not only below the headline hits, but also the structural relationship with the May hit of 1m at 4.49g/t gold.
Solstice says its latest results have elevated Bunjarra’s profile as a priority and it expects the prospect will join its other more advanced targets in the region in line for reverse-circulation (RC) drilling towards the end of this year.
Bunjarra sits on the eastern side of the interpreted eastern margin of the highly-prospective Keith-Kilkenny Tectonic Zone (KKTZ) – a deep crustal structural lineament that boasts many mineral prospects and projects, including the area’s Cosmo mineral occurrences such as Porphyry, 55km to the south, and Northern Star Resources' Carosue Dam, some 115km to the south.
The three successive phases of work represent a good example of economical exploration through composite sampling and analysis, with successful outcomes from disciplined re-assaying of individual intervals of interest.
Wagga Tank project – 130km south of Cobar, NSW
Hit: 2m at 6.45 per cent copper, 3000g/t silver and 0.78g/t gold from 112m.
Peel recently completed 15 vertical RC drillholes for 2240m, targeting potential supergene/oxide gold and copper mineralisation at its 87-square-kilometre, 100 per cent-owned Wagga Tank project near Cobar in NSW.
Copper-gold mineralisation at the site is related to primary stockwork/feeder mineralisation that occurs throughout the Wagga Tank-Southern Nights mineral system, which is believed to represent a major polymetallic volcanogenic massive sulphide (VMS)-style play. It is endowed with a combined indicated and inferred mineral resource of 6.83 million tonnes at 3.92 per cent zinc, 1.52 per cent lead, 0.24 per cent copper, 62g/t silver and 0.3g/t gold, making it an important part of Peel’s South Cobar project.
In 2016, the company’s drilling at Wagga Tank confirmed historic results and provided data that led to its 2017 discovery of the Southern Nights deposit, just 1km to the south.
In the past June quarter, a review of Wagga Tank’s historic drilling drew attention to supergene and oxide copper and gold mineralisation sitting immediately up-dip of the existing resource. The review concluded that zone was only thinly-tested and could represent a classic supergene zone related to weathering and alteration of typical VMS-style mineralisation at depth and that it warranted further drilling.
It then undertook about 2100m of RC drilling in late July and to date, assay results have come back only for the headline drillhole, which features significant supergene and sulphide mineralised intercepts. Results are pending for the balance of the program, including final silver analyses for the headline hole due to its unexpectedly high-grade 3000g/t silver response that exceeds the upper detection limit for the analytical method employed and requires re-assaying.
The upside there is that the big silver hit could point to more high-grade responses as the drilling progresses, especially as the headline geochemistry denotes a zone of shallow, supergene-style polymetallic base metal mineralisation.
More significantly, that shallow zone is followed by a deeper interval of intermixed massive sulphides, sulphide veining and quartz that returned 66m at 6.01 per cent lead, 3.73 per cent zinc, 0.98 per cent copper, 74g/t silver and 0.48g/t gold from 114m to end of hole at 180m. That broad zone of mineralisation also contains a high-grade interval including 6m at 20.14 per cent lead, 16.23 per cent zinc, 0.33 per cent copper, 194g/t silver and 0.45g/t gold from 164m.
The new mineralisation is open along strike to the north-east where there has been only minimal historic drilling, implying possible resource extension potential in that direction.
Significantly, considering the extension objectives of the program, the sulphide mineralisation in the headline hole sits about 20m west of and outside the current Wagga Tank-Southern Nights resource model and appears to be unconstrained along strike to the north. That theory is inferred from and supported by existing geophysics that highlight continuity of induced-polarisation (IP) anomalism, supporting possible mineralisation extension to the north.
The Wagga Tank and Southern Nights mineralised zones are connected by a thinly-tested “link zone” and together, the entire north-east/south-west extent of historic and Peel drillhole collars stretches over a distance of about 2.4km. The intercepts feature some of the highest-grade mineralisation returned to date from Wagga Tank and lie outside its existing mineral resource.
Peel was initially attracted to the Cobar region in 2010 by its endowment of world-class, high-grade, long-life base and precious metals-rich deposits such as those representing the CSA, Peak and Elura/Endeavor mines. Since the company’s entry into the Cobar district, it has assembled more than 3000sq km of tenure and defined significant mineral systems at its Mallee Bull, Wirlong, Wagga Tank-Southern Nights and May Day prospects.
In that period, it has completed more than 334km of drilling across its Cobar holdings, including about 289km of diamond and RC drilling. The bulk of the drilling, totalling about 249km of diamond and RC drilling, was committed to the general area of the South Cobar project mineral resource estimates.
Including the Wagga Tank-Southern Nights projects, Peel’s total combined mineral resource estimate for its South Cobar group of projects totals 19.75 million tonnes at 1.09 per cent copper, 0.76 per cent lead, 1.63 per cent zinc, 35g/t silver and 0.32g/t gold in both inferred and indicated categories.
Maverick Springs project – Nevada, USA
Hit: 13.72m at 137.9g/t silver and 0.34g/t gold from 231.65m (166.65g/t silver equivalent)
Sun Silver recently reported an exceptional intercept of 88.39m at 61.7g/t silver and 0.21g/t gold (79.6g/t silver equivalent) from 211.84m from a vertical extensional drillhole that intersected long, mineralised runs in the north-west part of its Nevada property.
The run included the headline hit that also included 1.52m at 508g/t silver and 0.16g/t gold (521.52g/t silver equivalent) from 289.56m. The drillhole is part of Sun Silver’s inaugural 7500m Maverick Springs drill program to evaluate a thick, high-grade zone in the north-west of the property beyond the existing mineral resource boundary.
The hole terminated in almost twice the thickness of mineralisation as exists in its nearest neighbour about 120m away and remains open at depth. The intercept confirms the company’s model that suggests thick, high-grade mineralisation could extend to the north-west beyond the limits of its recently-upgraded 423 million ounces at 67.25g/t silver equivalent mineral resource.
Assay results are yet to be returned for two more holes that also intersected high-grade mineralisation – as initially determined by pXRF readings. Sun Silver says that in addition to the silver and the accompanying gold credits, anomalous antimony readings up to 238.78 parts per million also continue to be returned as part of its lab assays.
Management says its latest results have proven its theory that wide, high-grade mineralisation extends to the north-west of the current resource area and provides strong momentum for the remainder of its extensional drilling program, with the results feeding into future mineral resource updates for Maverick Springs.
Yanrey project – 100km south of Onslow, WA
Hit: 5.9m at 374ppm uranium equivalent from 73.76m.
Cauldon’s headline hit included 1.2m at 789ppm uranium equivalent from 75.48m. A second hole also hooked 4.12m at 622ppm uranium equivalent from 61.48m including 2.24m at 908ppm from 62.02m.
The company says its first four AC drillholes have all intersected high-grade uranium mineralisation at its Manyingee South project that comprises a thick mineralised zone along a continuous 1.5km strike length, which currently remains open in all directions. Further drilling to test extensions of the identified mineralisation is in progress.
Cauldron’s 100 per cent-owned Yanrey uranium project covers an area of about 1270sq km, some 100km south of the WA town of Onslow.
It encloses more than 80km of Cretaceous-age sedimentary coastal units of the North Carnarvon Basin that are believed to be regionally-prospective for sedimentary-hosted uranium deposits in shallow unconsolidated sands (less than 100m).
Yanrey lies within a highly-prospective, mineral-rich region that contains multiple known economic uranium deposits, including Paladin Energy’s neighbouring Manyingee deposit featuring an estimated 25.9 million pounds of uranium-oxide from 13.8 million tonnes at 850ppm uranium equivalent. The project hosts multiple prospective paleochannel systems that have their source in uranium-bearing granitoid uplands to the east.
Cauldron’s Manyingee South (Target 15), about 4.5km south of Paladin’s Manyingee deposit, is considered a high-priority target. Additionally, the company’s ground also hosts its more advanced Bennet Well uranium deposit that contains 30.9 million pounds of uranium-oxide from 38.9 million tonnes at 360ppm uranium equivalent.
It puts Bennet Well into the class of a globally-significant project and metallurgical testwork has confirmed that its mineralisation is amenable to in situ leaching (ISL). And much of Cauldron’s Yanrey ground remains untested, with 22 high-priority targets identified for drilling.
Interestingly, logging of Cauldron’s drillholes points to strong analogues of its sedimentary units to those at Paladin’s adjacent Manyingee deposit. Of further significance to the overall extension potential in the region is that uranium mineralisation in Cauldron’s ground is interpreted as lying in a separate palaeochannel running parallel to the one that hosts Paladin’s resource.
With the biggest tenement holding in the region, Cauldron is well placed to explore for and identify further uranium deposits as it continues to assess prospective palaeochannel systems.
Is your ASX-listed company doing something interesting? Contact: matt.birney@businessnews.com.au
