Breaker Resources NL (ASX: BRB) reported that it has discovered several new high-grade lodes from the deeper drilling at its Lake Roe Project in Western Australia.
The company said that the diamond drilling to assess the underground mining potential below the 1Moz open pit Resource at Bombora has discovered several new high-grade lodes over a 1km distance, including the deepest drill intersections reported to date.
BRB said that all four drill holes intersected significant high-grade gold. Highlights include 4.6m @ 12.5g/t Au including 1.3m @ 42.7g/t within a broader zone of 19.6m @ 3.13g/t; 2.47m @ 12.1g/t Au including 1.37m @ 20.0g/t within a broader zone of 5.7m @ 5.56g/t; 2.65m @ 10.6g/t Au including 0.4m @ 67.3g/t; and 6.85m @ 4.8g/t Au including 1.4m @ 10.9g/t.
The company said that the results extend the strike length of known high-grade gold lodes below the open pit Resource by 600m to 2,000m (open both to the north and south).
BRB noted that the results indicate scope for a material increase in the Bombora Resource and significantly increase the potential for future underground mining below an extensively de-risked open pit Resource.
The company said that the results follow recent strong shallow RC drilling results from an emerging discovery at Kopai-Crescent, 3km north of Bombora, and continue to strengthen its belief that Bombora is part of a 9.5km-long gold camp still in the early stages of delineation.
Lake Roe project
Breaker’s large (600km2), 100%-owned Lake Roe project is situated between two established gold deposits, 100km east of Kalgoorlie in Western Australia.
Breaker had identified a significant new 6km-long gold system at Lake Roe in August 2015. Three subsequent phases of RC drilling resulted in three separate gold discoveries that now constitute one continuous 3.2km-long discovery called Bombora.
The 1Moz Bombora Resource is limited by shallow drilling to a vertical depth of 180m to 300m below surface and is open in all directions. Aircore drilling used to guide follow-up reverse circulation and diamond drilling, extended the Lake Roe gold system to 9.5km-long. The deposit is open in all directions after 240,000m of RC and diamond drilling.
The Bombora deposit shares many geological similarities to several well-known, Western Australian multi-lode dolerite-hosted gold deposits, such as the Golden Mile and Paddington.
Diamond drilling at Bombora
The company had recently completed four reconnaissance diamond drill holes below the northern part of Bombora on a 300m spacing.
The objective of the drilling was to scope out the potential for future underground mining below the open pit Resource ahead of targeted resource definition drilling. The drilling forms part of a long-term strategy aimed at building value by growing the resource base to expand and further de-risk the Company’s future development options.
BRB said that the results have highlighted the strong potential to expand the existing Resource at depth.
BRB said that the drilling relates to four, 300m-spaced reconnaissance diamond drill holes for 4,008m completed below the northern part of the Bombora open pit Resource, BBDD0092, BBDD0093, BBDD0094, and BBDD00096.
The company said that all four drill holes encountered significant gold mineralisation with visible gold present in several intersections, including the deepest reported to date at Bombora in two new steep lodes intersected in BBDD0096W2 situated ~600m below surface. Several new flat lodes were also discovered.
Significant results include 4.6m @ 12.5g/t Au including 1.3m @ 42.7g/t within a broader zone of 19.6m @ 3.13g/t (a new steep lode with visible gold) in BBDD0096W2; 2.47m @ 12.1g/t Au including 1.37m @ 20.0g/t within a broader zone of 5.7m @ 5.56g/t (a new steep lode with visible gold) in BBDD0096W2; 2.65m @ 10.6g/t Au including 0.4m @ 67.3g/t (new flat lode) in BBDD0092W2; and 6.85m @ 4.8g/t Au including 1.4m @ 10.9g/t (new flat lode) in BBDD0093W3.
BRB said that the results have extended the strike length of the high-grade gold lodes below the open pit Resource by 600m to the north and assay results are pending for BBDD0096W2 from 865m to end-of-hole (1,126m).
Breaker said that the outstanding new results demonstrated the sheer scale of the gold system at Bombora and its long-term growth potential. The company said that together with results reported from previous reconnaissance drilling at depth, this increases the overall strike length of known high-grade gold lodes below the open pit Resource to 2km.
The company announced the latest updates and the upcoming drilling plans for Bombora extensions, Carbineer prospect, and Kopai-Crescent area.
BRB said that the reconnaissance drilling on 300m-spaced sections will continue with the aim of scoping the high-grade gold potential below and north of the Bombora open pit Resource.
The company said that these framework drill holes will extend and supplement the broad structural controls of the gold mineralisation that have been established in the upper part of the Bombora deposit.
Breaker reported that the results of this drilling will then be used to plan resource definition drilling that will target Inferred mineralisation on a wide drill hole spacing which can potentially be mined underground at the appropriate time.
Breaker said that shallow diamond drilling is currently in progress 3km north of Bombora to follow up on strong shallow results from early, wide-spaced reverse circulation (RC) drilling in the Kopai-Crescent area.
The company said that this area is regarded as a potential emerging discovery and the diamond drilling will be used to guide ongoing RC drilling.
BRB reported that assay results are pending for a further 28 RC drill holes extending south of Kopai that targeted a potential link between the Kopai Prospect, and the Crescent Prospect, situated 1km to the south of Kopai.
It may be noted that the previous drilling at Crescent had outlined a 350m-long zone of continuous shallow gold mineralisation that is open to the north.
The company announced that the maiden RC drilling is currently underway at the Carbineer Prospect, a 3,200m x 500m area of oxide gold anomalism identified 700m east of the Bombora deposit.
BRB said that the anomaly was defined by wide-spaced (400-600m x 80m) sterilisation-focused aircore drilling in 2019.
The Carbineer target is broadly coincident with the sheared western margin of the Swan Lake Syenite and is adjacent to the regional-scale Claypan Shear, and has no pre-existing RC or diamond drilling.
Breaker Executive Chairman Tom Sanders said: “The success we have achieved through the recent shallow discovery 3km to the north, and now directly below the northern part of the 1Moz Bombora open pit Resource, shows the multiple options we have to grow the project – something that differentiates it from many of its peers.
The new drilling has confirmed a 2km strike length of high-grade gold mineralisation situated directly below an extensively de-risked open pit Resource, 80% of which is in the Indicated category.
The results highlight strong potential for a significant increase in the Resource at grades typically amenable to underground mining.
It’s also important to note that the high-grade lodes we are seeing at depth at Bombora are similar to the high-grade lodes present in the open pit Resource. In fact, in some cases, they are extensions of the same lodes but without a low grade halo that is typically applied in an open pit setting.
By varying the lower cut-off grade as shown at the back of this report, it becomes apparent that the mineralisation can be approached with either an open pit or underground mining scenario in mind.
Another way of saying this is that the Bombora deposit is high-grade by nature and this provides inherent mining flexibility or grade optionality, an aspect that tends to lower mining risk.
Not all projects are like this, and this has scope to add a lot of value to the project.
We have done the hard yards on the de-risking front, establishing the continuity in the upper part of the Bombora deposit after extensive drilling and 3D modelling as shown in this report.
We are now projecting the high-grade lodes over large distances at depth, and we either are hitting them with our reconnaissance drill holes, or discovering new lodes in the process, or both.
Based on the recent drilling, some of the individual flat lode systems are in excess of 1km-long, which matches the dimension of some of the west-dipping lodes in the shallow portions of the deposit. We believe that the continuity we see in the shallow portions of the deposit is likely to translate into a viable future underground mining scenario.”