The Lighthouse tenement (EPM 25617) is located approximately 50km southeast from the gold mining centre of Charters Towers in Queensland Australia. The project is an Intrusion-related gold/copper system involving high-level epithermal, mesothermal breccias and deep-seated porphyry targets. Lighthouse lies within one of the most productive structural corridors on the east coast of Australia, hosting Pajingo (2.4Moz gold), Mt Leyshon (4Moz gold, 2.3Moz silver), Ravenswood (+4Moz gold) and Charters Towers (+7Moz gold). Rockfire is targeting another Mt Leyshon-style and size of deposit.
Lighthouse has been explored by large, multinational corporations including Esso, Battle Mountain, Aberfoyle, Newcrest, CRA and Penarroya – all of whom usually had minimum targets of +2 million ounces of gold. More than 4,500m have been drilled within the Lighthouse tenement which comprises numerous prospects including Plateau, Bluff Creek, Double Event, Lower Lighthouse, Cardigan Dam and Split Rock.
The most advanced prospect is the Plateau Prospect. Plateau hosts gossanous and jasperlitic veins and gold-bearing breccia at the margin of a felsic (rhyolite) plug. Drilling at Plateau has intersected 4m @ 6.1g/t Au and 5m @ 6.55g/t Au, amongst other promising results.
Similar results have been encountered at the Double Event Prospect, where high gold values including 3m @ 5.20g/t Au and 2m @ 13.20g/t Au have been intersected in drilling, along with high silver values of 2m @ 17g/t Ag. The Bluff Creek Prospect has also been drilled with 4m @ 5.80g/t Au being successfully intersected in drilling.
This initial drilling has confirmed that high grades are achievable at each prospect and these intersections demonstrate the ability of the Lighthouse Project to host multiple, high-grade gold deposits.
Rockfire aims to further explore the Plateau Project, as well as follow-up anomalies outlined by previous explorers elsewhere within the tenement. Additional drilling at Plateau could see this project become another significant gold/silver project in the Charters Towers region.
At Plateau, previous exploration has identified high grade gold and silver at the brecciated southern margin of a felsic plug. Outcrops of gossan, alteration by silica, magnetite and chlorite are vectors identified by previous mapping campaigns. Drilling of gossans on the southern margin has intersected high grade gold in most holes, however the remaining margins of the felsic plug and the northeast faults have been poorly tested to date.
Aberfoyle Exploration summarised the potential for Plateau to host a high-grade gold deposit and provided compelling evidence that Plateau is identical to Kidston and Mt Leyshon gold deposits;
- Plateau occurs on the northeast trending Pajingo Lineament
- Identical Permo-Carboniferous felsic (rhyolitic) intrusives
- Similar lead isotopes, base metal association and alteration to Mt Leyshon, Ravenswood, Mt Wright and Kidston
- Geometry of plug unknown but surrounded by hydrothermal breccia and veining
- Surrounding areas covered by laterite have only received wide-spaced drilling
- Plateau has a geophysical signature of high K and magnetic low similar to Mt Leyshon
- Plateau has returned potential “ore grade” intercepts from a district that has produced +10M ounces gold
Newcrest completed detailed mapping and an air magnetic survey which indicate that the Plateau deposit is hosted within a large-scale hydrothermal system, of which only a small fraction has been drill tested. Rock samples taken over the hydrothermal system frequently return grades over 1.0g/t Au, with the highest recorded rock sample being 116.0g/t Au. Potential exploration success is considered high, both in testing new zones of mineralisation within the hydrothermal system, and further defining gold mineralisation down-dip of the drill tested zones.
Rockfire aims to explore and fully understand the breccia/stockwork and gossans in an effort to define a medium-scale gold resource at Plateau.
The earliest reports on exploration for the Lighthouse tenement date back to 1973 when Cormepar Minerals Pty Ltd applied for ground on the basis of prospectivity for gold and base metals. During its tenure, Cormepar undertook geological and geochemical investigations including the collection of 347 stream samples and 247 rock chip samples. Scattered (non-contiguous) geochemical anomalies were identified within the Lighthouse tenement. No analysis of precious metals was undertaken.
Highest copper-in-stream (145 ppm), lead-in-stream (481 ppm) and zinc-in-stream (930 ppm) were identified northwest of Plateau. The copper content in streams draining the Split Rock area is consistently higher than samples from other areas. Follow-up sampling close to the Plateau Prospect returned high grade copper up to 8.8% Cu, gold up to 3g/t Au and silver up to 30g/t Ag.
During 1976, Penarroya (Australia) Pty Ltd completed aerial photography, a soil sampling survey (136 samples collected), a regional stream sampling program (1,194 total) and further soil sampling including the collection of 3,582 samples. Thirty-three rock samples of outcropping gossans were also taken from the Plateau Prospect.
As part of the on-going campaign, Penarroya collected a further 193 soil samples and 120 stream samples in 1979 around the immediate area of Plateau. At the conclusion of the 1979 field season, Penarroya geologists concluded that “…assuming that ore grades of Cu, Pb, Zn exist within the fault zone, a speculative two million tonne deposit could exist.” Eeson B et al., (1980).
In 1980, Penarroya undertook the first round of drilling at Plateau. Four (4) RC holes for 591m were drilled. Hole 1 was abandoned due to caving, Hole 2 intersected 166m of pyrite, Hole 3 intersected 54m of pyrite and Hole 4 intersected a 9m wide zone of pyrite. No gold was analysed.
Esso Australia Ltd acquired the licence in 1983 and undertook a review of previous exploration and undertook follow-up work including gossan sampling, geological mapping, ground magnetics, IP, petrology, UTEM, soil sampling, air photography, aeromagnetics, resampling of Penarroya drill holes and trenching.
Esso collected 685 soil samples from the Plateau Prospect, followed by 876m of core drilling (3 holes), 350m percussion drilling (4 holes) and 126m of pre-collar drilling for a total of 1,352m. This is the first exploration campaign which analysed for gold and impressive drilling results for gold were encountered including: 3m @ 4.87g/t Au, 3m @ 3.38g/t Au, 89m @ 1.57g/t Au, 5m @ 2.77g/t Au, and 40m @ 1.37g/t Au.
A total of 1,260m of trenching was undertaken during the 1985 field season with results including 40m @ 1.37g/t Au (Trench 3700E). Esso also sampled the surface gossan at Plateau, which returned a 116g/t Au assay.
During 1987, at the Plateau Prospect, City Resources Ltd undertook geological mapping, rock chip and gossan sampling, spectral analysis and extensive geophysics including ground magnetics, IP and Mise-a-la-Masse. Anomalous rock samples around the main rhyolite at Plateau identified a number of additional targets for follow-up drilling. Results from this rock sampling exercise include 12.1g/t Au, 7.4g/t Au and 6.96g/t Au.
In early 1988, City drilled 30 RC drill holes for 1,670m at Plateau and a single water bore. Values up to 16g/t Au were intersected in drilling which tested gold mineralisation down to 60m vertical depth. Best results from this drilling include: 8m @ 3.03g/t Au, 10m @ 5.01g/t Au, 14m @ 2.44g/t Au, 6m @ 3.20g/t Au, and 4m @ 4.79g/t Au.
CRA Exploration Pty Ltd farmed into the exploration licence with City and commenced regional and semi-regional geophysics. During 1989, CRA completed geological mapping, stream sediment BLEG sampling, rock sampling, ground magnetics and radiometrics.
From 1992 through to 2008, exploration field work by various companies including Aberfoyle, Liontown, Plutonic and Newcrest focussed on other regional prospects and very little work was undertaken within the Lighthouse tenement itself. Only Newcrest undertook more drilling at Plateau.
Newcrest Mining Limited drilled a single 853.7 m deep drill hole (PLDD06001) at Plateau in 2007. This hole was designed to test the rhyolite plug and mineralization at depth beneath the southern edge of the rhyolite. This hole was an outstanding success and intersected the projected mineralised lode at the edge of the felsic plug more than 500m vertically below the drilling closer to the surface. The drill hole intersected 2m @ 1.0g/t Au and +30g/t Ag, confirming that the structure and associated gold and silver mineralisation continues to at least 500m vertical below surface. This offers the possibility for a large, mineralised system extending to this depth and beyond.
An assay of 1m @ 102g/t Ag was also intersected mid-way through the hole at 411m deep. Seven spatially separate one-metre intersections occur throughout the hole which assay above 20g/t Ag.
Kagara Resources Limited, Liontown Resources Limited and Ramelius Resources Limited all held ground around the Lighthouse tenement between 2009 and 2013 but most of the work completed by these companies involved semi-regional surface geochemical sampling.
Battle Mountain Ltd acquired the Lighthouse licence area in 1987 and drilled 25 RC holes for 798m. Early records show historical production from Double Event of 1,889tons returning 1,744 ounces of gold (average grade of 28.71g/t Au). At Double Event, a length of lode approximately 400m long had 5 holes drilled (LTR8-11 & 13) to test this strike.
During 1990, Western Mining Corporation Limited was undertaking preliminary rock chip sampling (involving 179 samples) at the Double Event Prospect, with an additional 48 dump samples collected. Rock samples returned high-grade gold including: 87.00g/t, 65.00g/t, 61.00g/t, 60.00g/t, 58.50g/t, 58.00g/t, and 55.5g/t Au. The average rock sample grade was 8.00 g/t Au.
Similarly, the dump samples were strongly anomalous with results including 8.10g/t Au and 5.18g/t Au. Without further drilling, WMC withdrew from the area citing that Double Event did not meet the criteria set by the company.
Pan Australian Mining Limited commenced exploration at the Lower Lighthouse Prospect in 1990 as part of the Lighthouse tenement. Geological mapping, rock chip sampling, trenching and RC drilling were undertaken during the first year of tenure with encouraging results.
Twenty-four (24) rock chip samples were taken in and around the old workings at Lower Lighthouse with very high-grade gold being returned including 11.40/t, 12.80g/t, 15.80g/t, 23.00g/t, 36.00g/t, 33.00g/t and 13.60g/t Au. Following such high results, PanAust dug a total of 14 trenches for 127m, with an average trench depth of 8m. Additionally, 11 RC drill holes were drilled for a total 405m. Highly anomalous results were achieved at 6 of the 14 trenches including 1m @ 3.47g/t Au, 1m @ 3.66g/t Au, 1m @ 2.45g/t Au, and 1m @ 2.35g/t Au. Follow up drilling intersected significant results from 5 of the 11 holes. Some of the holes do not appear to have been drilled close enough to the outcrop to intersect the main lode and may have been drilled too far away from the mineralisation. Drilling results include: 2m @ 0.77g/t Au, 4m @ 1.46g/t Au, 6m @ 0.37g/t Au and 2m @ 0.78g/t Au.
In 1992, Mt Leyshon Gold Mines Limited drilled 6 RC holes for 258m at the Lower Lighthouse Prospect. Best results from this drilling were 2m @ 6.25g/t Au (from 12m deep), 2m @ 1.5g/t Au (from 8m deep) and 2m @ 1.92g/t Au (from 12m deep) from 3 different drill holes. No further work was undertaken.
The Bullseye Prospect was first sampled in 1985 by Esso Australia and eight (8) reconnaissance rock chip samples were taken. Results include 0.15ppm Au, 0.1% Cu, 0.1% Pb, 0.1% Zn, and 15ppm Ag.
Dalrymple Resources NL undertook shallow drilling at the Bullseye Prospect in 1991 with very encouraging results for zinc mineralisation. In particular, hole BLP002 was anomalous in zinc above 1000ppm for its entire length of 108m, with a higher-grade zone of 6m @ 0.88% Zn only 50m from surface.
In 1992, Aberfoyle Resources Limited undertook reconnaissance sampling, ground magnetics, geological mapping, and stream BLEG sampling around the Split Rock Prospect (previously called Horse Creek) but no drilling was undertaken.
Ramelius drilled two RC holes at Horse Creek and the RC chips are available in Rockfire’s core yard in Charters Towers. The two holes hit low-level gold and copper mineralization but the holes are extremely altered. Alteration grades downhole from epidote-rich, through iron/magnetite and finally into silica alteration towards the bottom of each hole. The entire alteration package is approximately 60m thick and each hole terminates in strong alteration.
Previous rock chip sampling gold results at the main zone returned a number of high-grade intercepts including 116.0g/t Au, 8.39g/t Au, 13.9g/t Au. Gold results at multiple, sub-parallel outlying fault zones also returned a number of high-grade intercepts (6.9g/t Au, 3.45g/t Au and 4.9g/t Au). Both zones are laterally extensive and require additional drill testing; the outlying zones are currently undrilled.
Historical soil sampling at Plateau did not analyse for gold. The eastern section of the main zone of known mineralisation is strongly anomalous in copper.
Drilling at Plateau has not been systematic. Sixty two (62) RC drill holes, four (4) diamond tails, and four (4) full diamond drill holes have been drilled over a strike length of approximately 800m. High-grade drilling results include 3m @ 4.89g/t Au & 30.3g/t Ag, 5m @ 7.46g/t Au & 22.4g/t Ag and 5m @ 6.55g/t Au & 52.6g/t Ag. Plateau is open at depth, along strike and hosts multiple, un-drill tested, sub-parallel, fault zones which warrant drilling.
Cardigan Dam (Au-Cu)
Historical rock chip sampling has been sporadic at Cardigan Dam. Gold-in-rock results at the central main zone returned high-grade intercepts including 11.4g/t Au, 5.6g/t Au and 5.4g/t Au), along with a single bonanza grade of 1000g/t Au. Copper results are anomalous but low-grade (0.1 % Cu).
Soil sampling shows potential for a strongly mineralised gold (+/- copper) bearing system. There is a main central zone which is orientated east-west, along with a north-eastern zone which is not fully defined. The strong gold and copper anomalism make Cardigan Dam a highly prospective exploration target.
Twenty-two (22) historical, vertical RAB holes have been drilled north of Cardigan dam, however none of them test the gold-in-soil anomaly or the elevated rock samples. For this reason, Cardigan Dam is considered to be un-drilled.
Split Rock (Cu-Au)
Historical rock chip sampling returned high-grade copper results including 11.3% Cu, 5.0% Cu and 4.6% Cu. Along with copper, rock samples also returned anomalous gold (3.47g/t Au and 3.65g/t Au) and anomalous silver (38.1g/t Ag). These results occur over a strike length of over 800m, making Split Rock a high-priority target. The orientation of the anomalous rock samples is north-northeast.
Soil sampling in 1992 was conducted using a 25m east-west sample spacing and 100m north-south line spacing. No anomalous gold, copper or silver was identified.
Two drill holes have been drilled at Split Rock by Ramellius. The two holes hit low-level gold and copper mineralization but the holes are extremely altered. Alteration grades downhole from epidote-rich, through iron/magnetite and finally into silica alteration towards the bottom of each hole. The entire alteration package is approximately 60m thick and each hole terminates in strong alteration
Double Event (Au)
Rock sampling at Double Event was completed on a high-density pattern. The average grade of the 287 rock samples taken is 7.8g/t gold and 11.1g/t Ag.
Amongst the high-grade rock samples are some extremely high-grade gold results including 87.0g/t Au, 65.5g/t Au, 65.0g/t Au and 62.0g/t Au. These high-grade precious metal results were obtained over a strike length of 2,600m.
Rock sampling has also discovered a secondary mineralised fault system which occurs approximately 100m north of the main lode which is also characterised by high-grade gold values up to 20.26g/t Au. This provides opportunity for multiple, sub-parallel mineralised lodes to be identified at Double Event.
No significant soil sampling has been undertaken at Double Event.
Twenty-five (25) RC drill holes were drilled by Battle Mountain in 1987. This drilling targeted the top 25m from surface. This drilling intercepted high-grade gold zones including 2m @ 13.2g/t Au, 4m @ 4.6g/t Au and 2m @ 4.6g/t Au.
The high-density of consistantly high-grade rock samples at surface, together with encouraging drilling results make Double Event a high priority target for Rockfire.
Bluff Creek (Au)
Rock sampling undertaken by previous explorers returned high-grade gold and silver results (47.0g/t Au and 16.0g/t Ag). The mineralisation is centralised in multiple, sub-parallel fault zones which have a west-northwest strike. Rock sampling covers an area approximately 300m by 200m but is sparsely sampled. Additional rock sampling is recommended.
No soil sampling exists at Bluff Creek.
Ten (10) historic RC drill holes were drilled by Mt Leyshon Gold Mines in 1992. Best results include 2m @ 7.3g/t Au and 2m @ 6.8 g/t Au. Future planned work includes geological mapping, systematic rock sampling and additional drilling.
Lower Lighthouse (Au)
Historical rock sampling at Lower Lighthouse identified significant gold-silver results including 36.0g/t Au & 18.0g/t Ag, 33.0g/t Au & 15.0g/t Ag and 23.0g/t Au & 12.0g/t Ag. The average grade of all rock samples taken is 10.8g/t Au and 10g/t Ag. The mineralisation occurs in fault zones striking east-west.
No soil sampling exists at Lower-Lighthouse.
Historical drilling involves drilling eleven (11) RC holes completed by PanAust in 1990. Drilling was orientated towards the south with a best result of 4m @ 1.4g/t Au. Confirmation of the orientation of the mineralisation is required and structural mapping in planned to provide this confirmation.