ABM Resources NL (ASX:ABU) is pleased to announce that further reconnaissance surface work has uncovered a series of high-grade gold-bearing quartz veins between the Eastern and Western Limbs at the Old Pirate Deposit. These quartz veins contain coarse visible gold and are named the Heartland veins.
Highlights from Heartland vein sampling at Old Pirate:
Surface vein sampling at the Heartland Vein 1:
- 62 metres of strike length surface sampling averaging 82.25g/t gold
- Peak individual value 751g/t gold.
Surface vein sampling at the Heartland Vein 2:
- 29 metres of strike length surface sampling averaging 16.93g/t gold
- Peak individual value 133g/t gold.
Surface vein sampling at the Heartland Vein 3:
- 8 metres of strike length surface sampling averaging 37.17g/t gold
- Peak individual value 267g/t gold.
Surface vein sampling at the Heartland Vein 4:
- 7 metres of strike length surface sampling averaging 12.13g/t gold
- Peak individual value 142g/t gold.
Overall exposed high-grade vein strike sampled by the Company in the past two years
- 1.66 kilometres of combined strike length from multiple veins averaging 27.14g/t gold.
Darren Holden, Managing Director, said, "The Heartland Veins at Old Pirate are a series of quartz veins with spectacular visible gold that were previously not identified at surface. These veins dont naturally outcrop but were exposed as we cleared drill pads. These veins sit between the Western and Eastern high-grade limbs at Old Pirate. The Heartland veins will be incorporated in the open pit design potentially reducing the overall strip ratio and increasing the total ounces per vertical metre.
The Heartland veins are a series of quartz veins located between the Eastern and Western Limb lodes of the Old Pirate Deposit. These veins do not naturally outcrop and were uncovered by conducting reconnaissance trenching and clearing of drill pads in this area. The veins are steeply dipping and were covered by 30 centimetres of soil cover. They consist of narrow quartz veins with high-grade visible gold. Unlike the Eastern and Western Limb lodes the Heartland veins are not parallel with the shale stratigraphy. The Heartland veins cross-cut the stratigraphy. Whilst the veins fall within the existing resource modelling area they were not previously included as projecting to the surface. Previous drilling in the vicinity of the Heartland veins intersected assays up to 9.5g/t gold directly underneath the new exposed Heartland veins (hole OPRC040) and 140g/t gold (OPRC100001) down-plunge and along strike of the new exposed veins with further drill results from this area and other Old Pirate extensions pending assay and compilation.
Since 2011 ABM has been conducting longitudinal strike length sampling to understand the statistical characterisation and distribution of high-grade gold at Old Pirate. Overall there are over 1.66 kilometres of high-grade gold-bearing quartz veins (Table 5) that have been exposed and sampled as well as lower grade zones not included in the table below. Further results are pending.
2012 Vein Discoveries, Implications for Resource Development and Next Steps
ABM has explored Old Pirate since 2010. It was the innovation of using systematic surface sampling in mid 2011 that allowed the Company to better understand the coarse gold and the associated statistical nugget effect. In April 2012 the Company announced a maiden inferred and indicated resource totalling 565,000 ounces of gold averaging 10.5g/t gold (uncut) at Old Pirate (refer Appendix 2).
Recent metallurgical test-work indicates that gold liberates readily from the quartz veins using simple crushing and gravity separation methods. Further to existing resource estimation, ABM has conducted extensional exploration drilling, extensional surface sampling and has also drill-confirmed a new discovery at the Golden Hind Prospect located 800 metres south of Old Pirate.
Old Pirate sits on the same exploration license as the large-scale / bulk-tonnage Buccaneer Porphyry Gold Deposit.
Upon assessment of the overall scale and completion of requisite studies over the Old Pirate project area, which includes base-line environmental surveys, the Company will be in a position to apply for a mining lease. Environmental work has been conducted in tandem with on-ground exploration. The Company has also recently applied for a permit to conduct a 10,000 tonne bulk sample / trial mining exercise at Old Pirate. The purpose of the trial mining will be to reconcile mineable widths, grade and metallurgical recoveries.
Surface Vein Sampling Rationale and Sampling Method
Gold in the Old Pirate area can be coarse (up to 5mm gold grains) and is hosted within quartz veins. However, the distribution of the gold within these veins is not uniform, and hence drilling will likely under-call the overall grade due to the fact that there is a less than 1 in 5 chance of intersecting mineralised grades in any particular part of the vein.
Upon advice from external consultants, rigorous and systematic sampling of the quartz along the strike length of veins at Old Pirate was proposed. This work is akin to grade control of the first mining bench at Old Pirate.
Over 700m of sampling was conducted in 2011 and combined with drilling to estimate the gold resources at Old Pirate (16/04/2012). ABM has recommenced the program in 2012 of which the on- going work is presented here. This information, along with statistical parameters and extents of mineralisation, will be used to aid with further drilling and resource work.
The process for the surface sampling program is:
1. Natural outcropping veins are mapped for location and width and sampled at 1 metre strike length intervals.
2. A small digger then exposes those parts of the veins that are hidden underneath shallow soil cover to provide a combined map of natural outcrop and exposed quartz vein.
3. For each metre of exposed quartz vein (both in natural outcrop and cleared veins) two representative samples of up to 10kg are collected. Quartz is selected systematically in a grid pattern so as not to bias individual samples. Both samples are sent to the laboratory.
4. The sample width depends on the width of the vein or exposed areas. In cases where the vein width is generally greater than 1 metre, multiple samples may be collected across the vein. On narrow portions of the vein (e.g. less than 20cm) estimating the actual width is difficult due to the oxidised surrounding shale being intermingled with the vein.
5. The maximum depth of the digging is 60cm (due to permit regulations, safety considerations and to minimise environmental impact). If the soil cover is greater than 60cm then sampling does not take place despite the likelihood of the vein continuing beneath 60cm.
6. Samples are processed by ALS Global in Alice Springs (NT), and ALS Global in Perth (WA) where they are weighed and analysed using regular fire assay (AA26D). Samples greater than 100g/t are re-assayed using AA26D / Over Limit Dilution method.
7. Overall statistics and spatial distribution for vein strike length and grade are calculated by measuring sampled portions of vein (including a projection of short lengths (<10 metres) where the vein is inferred to have extended under cover) and then averaging all of the samples along the length. Individual entire veins that are un-mineralised (<1g/t) are excluded from overall statistics.
8. Samples are surveyed with a hand-held GPS using waypoint averaging for 20cm spatial accuracy.
9. Surface samples are weighted for sample width prior to being used in any resource estimation work.
View the complete ABM Resources announcement including Tables and Figures at the link below: