Resolution Minerals Ltd (ASX:RML, OTC:RLMLF) has reported encouraging initial results from its maiden diamond core drilling program at the Golden Gate Target within the Horse Heaven Gold-Antimony-Tungsten-Silver Project in Idaho, USA.
The company has completed four holes totalling 960 metres of a planned 3,000-metre Phase 1 program of up to 12 holes. Early work has revealed host rock mineral textures comparable to those at Perpetua Resources’ adjoining Stibnite Gold Project, while scheelite, a tungsten ore mineral, has been identified under ultraviolet light in three of the first four holes.
Location plan of the Horse Heaven Project, with inset showing key prospects. (Note: Coordinates are UTM metres north and east metric system, not latitude/longitude.
Resolution aims to confirm historical shallow drilling results and expand the mineralised footprint, with assays for antimony, tungsten, gold and silver to follow. A fifth hole is currently underway.
“The drilling is more encouraging than initially expected, with alteration textures similar to the adjoining Stibnite mine and visible tungsten as scheelite in all logged holes to date. Initial assay results are eagerly awaited, not just for gold and silver, but for tungsten as well, which had not been assayed for in this area, despite previous workings,” Resolution’s US Operations chief executive Craig Lindsay said.
“What is also exciting is that this target is only a postage stamp size in a much larger project.”
Initial drilling results and geological observations
Resolution’s Phase 1 diamond core drilling at Golden Gate is designed to test up to 12 holes over 3,000 metres.
Four HQ-sized holes have been completed to depths of around 260 metres. The predominant lithology is bleached, altered and locally oxidised quartz-sericite to silicified felsic granite, believed to be part of the Cretaceous Idaho Batholith.
Local technical experts have confirmed that alteration, low-temperature epithermal mineralisation and vein textures observed in the drill core are very similar to those at the Stibnite Gold Project.
Quartz veins associated with fine-grained sulphides and sheared fault gouge with sulphides were noted. Visual mineralisation in the form of scheelite was confirmed in three holes using ultraviolet light, although assay results will be required to quantify tungsten and associated mineralisation.
Scheelite identification
The use of ultraviolet lamps on drill core revealed the diagnostic sky-blue fluorescence of scheelite at several intervals, including 73.0–73.15 metres in HHGG25-002 and shallow zones in HHGG25-003.
Sections of drill core from Drillholes HHGG25-002 & - HHGG25-003 at the Golden Gate Target of the Horse Heaven Project, with drill core on the left and the same drill core exposed under shortwave UV light on the right indicating the presence of scheelite (tungsten mineralisation CaWO3).
(a) Upper-most images: Photo of drill core sample from Drillhole HHGG25-003 (2.0ft to 2.5 ft downhole depth) showing a heavily oxidised mineralised quartz-feldspar altered intrusive, with manganese quartz veins and disseminated 4% scheelite estimated of core section. For clarity: Mineralised mineral: Disseminated scheelite (4%).
(b) Central images: Photo of drill core sample from Drillhole HHGG25-003 (9.9ft to 10.8 ft downhole depth) showing an oxidised manganese-quartz mineralised vein cross-cutting altered quartz-feldspar intrusive, with 2% scheelite estimated of core section. For clarity: Mineralised mineral: Vein type scheelite (2%).
(c) Lower-most images: Photo of drill core sample from Drillhole HHGG25-002 (239.5ft to 240ft downhole depth) showing an oxidised mineralised quartz vein cross-cutting altered quartz-feldspar intrusive, with 0.5% scheelite estimated of core section. For clarity: Mineralised mineral: Vein type scheelite (0.5%).
Scheelite had not been previously assayed in historical drilling, despite the region’s history as a tungsten supplier to the US government during the 1950s.
Resolution cautioned that fluorescence is not an indicator of grade or abundance and cannot substitute for laboratory assay results. Although visual scheelite may be associated with gold mineralisation, only laboratory analysis will confirm grade and continuity. Assay results from the current program are expected within six to eight weeks.
Historical context and drilling plans
Past drilling at Golden Gate produced gold intersections of 85.34 metres at 0.937 grams per tonne (g/t) gold, including 38.10 metres at 1.459 g/t, and 30.48 metres at 1.354 g/t. The present program seeks to validate these results while also expanding knowledge of the antimony, tungsten and silver potential.
HHGG25-003 drill core at the Golden Gate Target displaying quartz sericite-chlorite altered monzonite with fine grain disseminated sulphides and chalcedonic quartz-sulphide veins and stockworks. Field of view is 60cm (left) and from a depth of 204m to 206.7m (669.2-678.4 ft) in HHGG25-003. This photo of core is included in this announcement to show the high degree of veining and alteration. It does not allude to any form of mineralisation.
Resolution is considering accelerating drilling with a second rig to complete the program by October 2025. Structural analysis will follow, enabling estimation of true widths of mineralised zones. The company emphasised that Golden Gate is a small portion of the broader Horse Heaven Project, which covers 699 federal lode mining claims across 5,644 hectares.
Next steps
Resolution plans to submit selected intervals for multi-element assay testing, focusing on zones with visible scheelite.
Results will determine the scale and direction of further exploration across the Horse Heaven Project.