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Suite 9, 36 Ord St
West Perth, Western Australia 6005

Tel: +61 8 6555 3980
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Munarra Gully Cu-Au Project, Cue Western Australia

Exploration Target: Multiple copper-gold bearing mafic (norite) intrusions.

  • The style of mineralisation is likely magmatic and is atypical with respect to mineralised mafic intrusive systems due to high Cu:Ni ratios, high Au and Ag, low S and elevated PGM’s.
  • The style is similar to known large copper rich mafic intrusive (ortho-pyroxenite) historical deposits in Brazil (Caraiba mining district – 96Mt @1.82% Cu reserve and production) and South Africa (Okiep mining district – Koperberg – 94Mt @ 1.75% Cu historic production). Gold, silver and PGM’s are associated with these copper deposits.

Rumble Resources Ltd and option agreements to acquire 80% of tenements E51/1677 and M51/122 that form the Munarra Gully Cu-Au Project with Ni – Co potential some 50km NNE of the town of Cue within the Murchison Goldfields.  Previous exploration has focused generally on gold with shallow RAB and RC drilling on both tenements.

Significant Cu-Au Discovery at Munarra Gully 

In August 2018 Rumble coompleted its maiden drill program which consisted of seven (7) RC holes for 1149m.

Four (4) drill-holes (WRRC-001 to WRRC-004) were designed to test the primary zone below two small open cuts at the main White Rose Prospect. Two traverses, 160m apart were completed. Widespread copper and gold mineralisation in oxidised ultramafic/mafic had been exposed in the open cuts by the current owner. The open cuts (active operation) have a maximum depth of nearly 20m. Historic RAB drilling focused on gold and was confined to shallow oxide (vertical depth of 32m).

All drill-holes (four completed on the White Rose Prospect) intercepted widespread significant copper- gold mineralisation. See figures  2 and 3.

  • Copper and gold are associated with disseminated sulphide (chalcopyrite and bornite) mineralisation hosted in orthopyroxenite (norite) intrusive. RC drilling intercepts include:
  • ⃰ WRRC001 – 22m @ 1% Cu from 29m coincident with 19m @ 2.19 g/t Au from 33m. Maximum Cu was 2.66% (40-41m). Maximum Au was 11.56 g/t (49-50m). 
  • ⃰ WRRC002 – 10m @ 0.74% Cu from 75m coincident with 11m @ 0.73 g/t Au from 75m.
  • ⃰ WRRC003 – 26m @ 0.79% Cu from surface and 7m @ 0.64% Cu from 28m. In addition, 5m @ 1.17 g/t Au from 13m, 5m @ 0.71 g/t Au from 20m and 9m @ 1.64 g/t Au from 27m.
  • ⃰ WRRC004 – 23m @ 0.54% Cu from 45m and 6m @ 0.66% Cu from 70m.

                                                ⃰ 0.3% Cu and 0.3 g/t Au lower cut-off and true intercept width unknown

                  

                                                     Figure 1. RC Drill section 615325E – White Rose Prospect

The disseminate sulphide mineralisation at White Rose is hosted in generally fine grain undifferentiated orthopyroxenite/norite to dolerite rock types. The rocks are magnetite bearing. Ag is strongly elevated (to 11.4 g/t Ag). PGE (platinum group elements) assay results are pending. The higher order copper-gold mineralisation lies within the mafic rocks immediately adjacent to the contact with ultramafic (>10% Mg) rocks.

The deposition style is considered very significant as it potentially represents copper bearing mafic/ultramafic intrusive related mineralisation. Examples include the Caraiba Cu mining district in Brazil (production and reserve - 96Mt @ 1.82% Cu) and the Okiep (Koperberg) Cu mining district in South Africa (historic production - 94Mt @ 1.75% Cu) – see overview section below.

Air Core Drilling Completed December 2018 (see Figure 1)

During December 2018, five shallow air core drill traverses tested for potential strike extensions to significant copper-gold mineralisation discovered by RC drilling (refer ASX announcement 30 August 2018).

Shallow air-core drilling has extended the strike potential of the copper-gold mineralisation to over 800m, significantly adding scale potential to the project – strike open west and northeast.

A total of 50 angled air core holes (blade refusal only) for 1099m were completed. The average drill hole depth was only 22m (15m vertical), as the programme was designed to highlight the copper – gold geochemistry in the upper weathered basement. The White Rose Prospect has undergone an extended period of alluvial gold mining. This historical work has disturbed the surface and therefore doesn’t allow for traditional soil/lag sampling methods.rom composite sampling (4m and 2m composites), a 1000 ppm Cu (0.1% Cu) contour has outlined copper mineralisation in the surface/upper basement zones. The air core drilling has extended copper mineralisation some 300m to the northeast of the open cuts with anomalous gold (using 100ppb Au). Copper anomalism occurs over a width up to 80m. The trend is potentially open to the northeast as low order Au (50ppb contour) and elevated Cu (400ppm) were encountered with very shallow drilling. Immediately west of the open cuts at White Rose, a large north-northeast trending mafic dyke has intruded along a fault zone and the copper-gold mineralisation has been displaced some 200m to the north. Strong copper – gold mineralisation was encountered on the westernmost air core drill traverse over a width of 70m. Intercepts include:

  • WRAC037 - 33m @ 0.17% Cu from surface (entire hole)
    • includes Cu to 0.38% and Au to 0.74 g/t
  • WRAC036 - 33m @ 0.15% Cu from surface (entire hole)
    • includes Cu to 0.35% and Au to 0.21 g/t

The air core drilling intercepted highly weathered mafic and ultramafic intrusives under shallow hardpan (1 to 2 m depth). Discrete areas of strong silica alteration were encountered along with late dolerite to gabbro dykes. Copper anomalism with Au has been defined over a strike of 800m and is completely open to the west and is potentially open to the northeast.

New Target Type: A north trending magnetic anomaly was tested by (4) four air core holes on the eastern side of M51/122 (see figure 1). Highly weathered pyroxenite was intercepted in shallow drilling. Moderate nickel anomalism was encountered with elevated copper (Ni to 4008 ppm and Cu to 1061 ppm). No gold was associated with the pyroxenite.

                                 Figure 2.         White Rose Prospect – Results of Air Core Drilling and Previous RC Drilling

The copper in lag anomalism occurs over a strike of 3.6 km and is open to the northeast under cover towards the White Rose Prospect.  Note: Approximately 4km of potential strike is under cover between the copper in lag anomalism and the White Rose Cu – Au mineralisation. This is a target that will be tested with future aircore drilling, to test for strike at depth.

Regional Geochemistry - E51/1677 

Infill and extension lag sampling (344 samples) complimented previous orientation lag sampling (107 samples) for a total of 451 samples and were collected on 200m by 50m and 200m by 100m spacings over a strongly magnetic northeast trending sequence of mafic volcanics with ultramafic and mafic intrusions. Four (4) significant, coherent copper anomalies have been highlighted, some with gold anomalism.

  1. Copper A1 Anomaly – 600m strike, up to 400m wide with copper to 437 ppm
  2. Copper A2 Anomaly – 500m strike with copper to 444 ppm
  3. Copper A3 Anomaly – 2000m strike with copper to 620 ppm and gold to 35 ppb
  4. Copper A4 Anomaly – 200m strike with copper to 916 ppm and gold to 19 ppb

                    Figure  3 – Munarra Gully Project Lag in Soil Cu Results, Geology and White Rose Prospect

Exploration Potential - Potential Mafic Hosted Magmatic Sulphide System

  • Copper and gold sulphide mineralisation associated with fine to medium grain undifferentiated orthopyroxenite/norite intrusive (mafic/ultramafic) rocks.
  • Copper and gold are associated with chalcopyrite and bornite. The mineralisation has very high Cu:Ni ratios with strong silver anomalism (to 11.4 g/t Ag). Platinum group elements assay results are pending.
  • The style of mineralisation has similar characteristics to known large copper rich mafic intrusive (ortho-pyroxenite) deposits in Brazil (Caraiba mining district – 96Mt @1.82% Cu reserve and historic production) and South Africa (Okiep mining district – Koperberg – 94Mt @ 1.75% Cu historic production). Gold, silver and PGM’s are associated with these copper deposits 

In the Caraiba Complex, Bahia Province, Brazil, numerous mafic/ultramafic irregular shaped intrusions hosted chalcopyrite-bornite mineralisation (predominantly in orthopyroxenite). The total reserve for the complex (including historical production) is estimated at 96 Mt @ 1.82% Cu.  The deposits are atypical of magmatic deposits in that magnetite may be up to 50%. The copper mineralisation is typically 70% chalcopyrite: 30% bornite. In addition, very high Cu:Ni ratios are the norm with associated Au, Ag and PGM’s. Gold is reported to 22 g/t. The copper bearing intrusives are hosted in amphibolite/granulite rocks (ultra-high temperature metamorphics).

A similar style of copper mineralisation has been mined in the Okiep mining province in South Africa (Koperberg suite). Historically some 94 Mt @ 1.75% Cu was mined from predominantly orthopyroxenites associated with numerous irregular shaped mafic to ultramafic bodies with characteristic high Cu:Ni ratios and very strongly anomalous Au, Ag and PGM’s.

 

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