Exploration Update, High Grade Au at Sandstone North
ASX Announcement 11 February 2019
HIGHLIGHTS
- Reverse Circulation (RC) drilling in progress at Havilah deposit to obtain samples for metallurgical test work to support JORC (2012) resource estimate (in progress).
- High grade gold mineralisation confirmed from previous explorers’ RC drilling at Sandstone North.
- Sandstone North high grade drill intercepts* include:
- RC drilling planned for Sandstone North Q1, 2019.
- Resource estimation at Havilah & Ladybird on track for completion by end February.
Compilation and review of previous explorer’s data has confirmed that high-grade gold mineralisation exists at the Sandstone North Prospect.
Reverse circulation (RC) drilling is planned for Q1, 2019, to test for along strike and down-dip/down plunge extensions to the mineralised zone.
Commenting on these results, Alto’s Executive Director Dermot Ryan said: “Sandstone North is somewhat different from other known gold deposits at Sandstone, in that the gold mineralisation is hosted in a sulphidic quartz vein system within sheared pyritic sediments, adjacent to an ultramafic unit. The high grade nature of the mineralisation and the under explored/under drilled nature of the deposit makes it an attractive exploration target for 2019.”
INTRODUCTION
The Sandstone North Prospect is located approximately 6km north of the town of Sandstone and lies approximately 1km east of the Sandstone - Wiluna road. The prospect includes the historic Oroya Extended workings where small pits and shafts extend north-south over a strike length of approximately 300m. Historical production is recorded at “223 fine ounces of gold from 282 tonnes of ore at an average grade of 24.6 g/t Au”
Figure 1. Location of Sandstone North Prospect over Regional Geology
Exploration Update for Ladybird Prospect Sandstone Gold Project, WA
ASX Announcement 30 January 2019
HIGHLIGHTS
- High grade gold mineralisation confirmed from previous explorers drilling at Ladybird.
- Significant downhole* RC drill intercepts at Ladybird include:
- MSGC1162 : 5m @ 29.4 g/t Au from 8m
- HKR006 : 4m @ 7.3 g/t Au from 42m
- TRC018 : 5m @ 5.6 g/t Au from 0m
- TRC010 : 3m @ 8.5 g/t Au from 12m
- MGC1387 : 5m @ 4.9 g/t Au from 10m
- MSGC1385 : 5m @ 4.6 g/t Au from 36m
- MSGC1123 : 5m @ 4.1 g/t Au from 67m
- HKR017 : 4m @ 5.1 g/t Au from 49m
- MSGC1122 : 3m @ 6.5 g/t Au from 21m
*Cautionary note: due to the steep nature of mineralisation, downhole widths are not true widths.
- Mineral Resource estimates (JORC 2012) in Progress and RC drilling Planned for Q1, 2019
Compilation and review of previous explorer’s data has confirmed that shallow high-grade gold mineralisation exists at the Ladybird Prospect. Although the mineralised zone is relatively narrow and steeply dipping, the grade and continuity of mineralisation suggests that the deposit could be amenable to open pit mining in its upper reaches.
Alto has commissioned Dr Spero Carras of Carras Mining Pty Ltd to prepare a JORC (2012) Mineral Resource Estimate for the Ladybird deposit. This should be completed in February 2019.
Further RC drilling is planned to test for along strike and down-dip extensions to the mineralisation which could potentially expand the mineralised zone.
Introduction
In 1986 Western Mining Corporation (WMC) carried out a regional lag geochemical survey which highlighted the historical Lady Mary prospect and also two anomalies to the NW and SE of Lady Mary. The anomaly 1km SE of Lady Mary (named “Ladybird”) reported peak assays of 380ppb Au and 280ppb Au on adjacent lines 400m apart.
The Ladybird Prospect is located approximately 25km SE of the town of Sandstone and lies approximately 3km north of the Sandstone - Menzies road. The prospect area is comprised of mafic and ultramafics rocks intercalated with thin sedimentary marker beds of chert and banded iron formation (BIF). The stratigraphy strikes NW-SE and has sub-vertical dips. Refer Figure 1 below.
Figure 1. Location of Ladybird Prospect over Sandstone Greenstone Belt Regional Geology
High Grade Gold Assays in 1m Samples from Vanguard RC hole SRC114, Sandstone, WA
ASX Announcement 5 December 2018
- One metre fire assay results from RC hole SRC114 confirm high grade at Vanguard
- 40 samples of 1m length returned the following intervals:
- SRC0114 : 40m @ 3.6g/t Au from 61m
- incl. : 5m @ 8.7g/t Au from 61m
- and : 19m @ 4.0g/t Au from 69m
- and : 7m @ 3.0g/t Au from 94m
- Individual 1m assays include: 1m from 63m @ 19.2g/t Au, 1m from 71m @ 15.1g/t Au, and 1m from 79m @ 11.9g/t Au.
Alto Metals Limited (ASX: AME) (“Alto”, “the Company”) is pleased to advise that high grade 1m assay results have been returned from Vanguard reverse circulation (RC) drill hole SRC114 drilled at Vanguard in September to confirm the geological model and provide samples for preliminary metallurgical testwork.
VANGUARD REVERSE CIRCULATION DRILLING
RC hole SRC114 (total 102m) was drilled to provide samples for preliminary metallurgical testwork. The 4m composite assay results and metallurgical test results (93-94% recovery) were reported on 15 October 2018.
The +1.0g/t Au fire assay results for the 1m re-split samples in SRC114 are shown in Table 1 below and in Figures 1 - 3. All +0.5g/t Au assay for 1m resplit samples are included in Table 3.
40m @ 3.5g/t Au Confirmatory Intersection from 60m Depth at Vanguard, Sandstone Gold Project, WA
ASX Announcement 15 October 2018
HIGHLIGHTS
- RC drilling confirms robust geological models at Vanguard and Tiger Moth. Intercepts into high grade zones include:
- SRC114 (Vanguard) 40m @ 3.5 g/t Au from 60m
- SRC115 (Tiger Moth) 8m @ 4.1 g/t Au from 52m
- Preliminary metallurgical testwork shows recovery of +92% gold from both oxide and primary gold zones
- Assay results from reconnaissance aircore (AC) drilling at Bulchina, Sandstone North and Vanguard Camp indicates potential for further shallow oxide gold mineralisation
- Step-out RC drilling at Indomitable Camp and Vanguard Camp deposits planned to test mineralised structures down dip/down plunge (outside 2018 JORC [2012] Mineral Resources)
- Maiden mineral resource estimation [JORC 2012] planned for Ladybird, Havilah and Sandstone North
Alto Metals Limited (ASX: AME) (“Alto”, “the Company”) is pleased to advise that assay results from 2 RC holes drilled in September at Vanguard and Tiger Moth to confirm the geological models and provide samples for preliminary metallurgical testwork have returned high recoveries and better than predicted grades.
Assay results received from reconnaissance aircore drilling at Bulchina, Sandstone North and Vanguard Camp indicates that these mineralised systems are still open, and further drilling is required.
Commenting on these results, Alto’s Managing Director Dermot Ryan said:
“Alto’s recently published Mineral Resource estimate [JORC 2012] for the Indomitable and Vanguard Camps was the result of applying a systematic exploration approach. This process resulted in the selection and successful testing of a number of litho-structural gold targets.
The next stage is to step-out and drill test the down dip/down plunge extensions of these newly discovered mineralised structures and convert gold mineralisation into mineral resource.”
REVERSE CIRCULATION DRILLING
During September, 4 shallow RC holes (total 356m) were drilled at Vanguard, Tiger Moth and Indomitable to provide samples for preliminary metallurgical testwork.
At Vanguard and Tiger Moth, RC holes SRC114 and SRC115 were drilled to 102m. At Indomitable, SRC116 and SRC117 were drilled but were abandoned prior to reaching the mineralised interval due to difficult drilling conditions. As a result, samples for preliminary metallurgical testwork at Indomitable were obtained from RC cuttings from drill hole SRC086 drilled in February 2018 by Alto. Assay results for SRC086 were previously released to the ASX on 20 March 2018 (refer ASX release 20 March 2018).
The +1.0g/t Au fire assay results for the 4m composite samples are shown in Figures 1 and 2 and in Table 1 below. All 4m composite samples +0.5g/t Au results are included in Appendix 1.
At Vanguard and Tiger Moth, the deeper and higher-grade gold intersections down plunge and external to the 2018 $2,000/oz Whittle pit shells were not included in the 2018 Mineral Resource estimate and require follow up RC and diamond core drilling with a view to enlarging the pits.
