Noricum Gold Limited, the European focused base and precious metals exploration and development company, has given DirectorsTalk an update on its exploration activities at the Company’s 100% owned Walchen VMS Deposit, located in an area of Austria proven to host copper, gold and silver mineralisation. In particular, the Company is pleased to tell us about the discovery of a large limonitic outcrop likely to represent an ore zone within the Project area, highlighting the potential of the area.
Highlights
— Completion of initial mapping and sampling programme has validated the Company’s strategy of moving into the Walchen region with both geology and initial results confirming a new and significant zone of outcropping mineralisation
— Large anomalous intercept with high grade hanging wall section has been returned from channel sampling of a highly oxidized and weathered Gossan:
o 12m @ 0.6% copper (“Cu”), 0.33 g/t gold (“Au”) and 7.25g/t silver (“Ag”)
o Including 2m @ 1.14% Cu, 1.08g/t Au, 30.8g/t Ag
— Further local rock and chip sampling returned results up to 1.03% Cu, 5.63% lead (‘Pb’), 12.65% zinc (‘Zn’)
— Non JORC mining inventory of 423,470 tonnes of ore calculated at completion of exploration in 1945 highlighted in recent literature searches
— On-going exploration activities focused on outcrops and underground workings – with these low cost work programs being completed in tandem with activities in Georgia
Noricum Gold Managing Director Greg Kuenzel said, “As demonstrated by historical evaluations and the discovery of a large limonitic ore zone within our licence area, Walchen has surprised us with its potential. The advantage to this project area is we can explore at speed and for a relatively low cost with a continuous stream of results from on-going exploration. It appears mineralisation is consistent and is outcropping along a significant strike length and with easy access we plan to map and sample the entire length of the outcrop. This work will be conducted in parallel with the expected initial work programmes at the newly acquired and more advanced Georgian VMS acreage. Our expanded portfolio now provides shareholders with exposure to multiple projects at various levels of development, from initial grass roots “discovery potential” through fast track resource calculations and development. The Company expects to update the market in the coming weeks as the results from these various work streams come to fruition.”
Mapping and Sampling Programme
The Company acquired the Walchen VMS Project in March 2015 and rapidly commenced a verification mapping and sampling programme. This was completed over a three week period ending in early July 2015. A total of 48 samples were taken during the programme comprising of dump, outcrop and channel samples.
This announcement details the samples collected during the field work period, WAL6 – WAL53. Of particular interest are WAL29-41 which represent a previously unmapped and unsampled limonitic outcrop to the west of the main mining area that have returned good anomalism for copper, gold and silver. These samples are two metre interval, channel samples across the whole outcrop, with around 26 metres of apparent width.
Samples WAL35-40 show the best anomalism and represent a 12 metre intercept across the outcrop: 12m @ 0.6% Cu, 0.33 g/t Au and 7.25g/t Ag. The highest grade was returned by WAL40 – 2m @ 1.14% Cu, 1.08g/t Au, 30.8g/t Ag.
Other sampling from dumps and rock chips returned results up to 1.03% Cu, 5.63% Pb, 12.65% Zn.
The eastern (hangingwall) part of the outcrop shows several metres of disseminated sulphides (mainly pyrite), followed by massive limonite (thickness of several metres; sometimes with malachite staining) and dark phyllite with limonite in the footwall section. This is obviously an outcrop of the ore horizon and the massive sulphides (usually rich in pyrrhotite) are completely decomposed, resulting in the formation of limonite. Several old mines are located below this outcrop (downdip of the ore horizon).
Highlights from the sampling programme:
Sample Type Au
no Cu (%) (g/t) Ag (g/t) Pb (%) Zn (%)
-------- ------------- ------- ------- --------- ------- -------
WAL-9 Rock Sample 0.15 0.46 166 5.63 12.65
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WAL-15 Rock Sample 0.50 0.67 42 0.20 0.69
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WAL-17 Rock Sample 1.01 0.21 27.8 0.63 1.62
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WAL-18 Rock Sample 0.36 0.07 7.94 0.23 0.28
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WAL-19 Rock Sample 1.03 0.12 11.1 0.14 0.28
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Channel
WAL-20 Sample 0.25 0.17 23.4 0.13 0.07
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Channel
WAL-35 Sample 0.42 0.26 2.1 0.04 0.19
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Channel
WAL-36 Sample 0.56 0.28 2.35 0.03 0.19
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Channel
WAL-37 Sample 0.40 0.08 1.05 0.03 0.21
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Channel
WAL-38 Sample 0.77 0.21 2.73 0.02 0.15
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Channel
WAL-40 Sample 1.14 1.08 30.8 0.38 0.41
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Channel
WAL-41 Sample 0.00 0.37 19.2 0.38 0.67
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WAL-42 Rock Sample 1.93 0.88 23.6 0.25 0.50
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WAL 43 Rock Sample 0.14 <0.01 1.42 0.00 0.00
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Walchen Overview
The volcanogenic massive sulphide (VMS) deposit of Walchen is located in the Eastern Alps, Styria Provence, central Austria. The deposit is 6km south-east of Oblarn, located in the Enns Valley and access is by sealed and then forestry roads. The nearest major town is Salzburg, 120km to the northwest.
The Walchen property hosts a previously producing mine, the data from which highlights the project’s prospectivity. In consideration of this, the Company commenced an initial exploration programme in tandem with on-going review of the historic data.
It is unclear when mining initially started at Walchen, possibly in the 1200s, but later in 1434 an operational smelter was described in historical literature. Mining became increasingly important through the 17 and 18th centuries and in 1824 an annual production of 34kg of gold, 2550kg of silver and 406 tonnes of copper was reported. A short hiatus in mining was followed by intermittent production again between 1891 and 1958 where pyrite was mined to produce sulphuric acid.
The Walchen deposit is interpreted as a product of submarine exhalative processes in a failed rift zone, typical of early earth evolution where mantle plume activity was the dominant feature in this case resulting in an extensional tectonic environment.
The host rocks are metamorphosed volcano-sedimentary sequences of Palaeozoic age. The mineralisation occurs in rocks that were originally pelites and sandstones with a hanging wall comprising continental alkali basalts.
The massive sulphide mineralisation was likely emplaced by hydrothermal processes caused by sub-seafloor fluid convection systems. Mineralisation can reach 4m in thickness comprising central massive sulphides surrounded by hanging and footwall disseminated and stockwork mineralisation.
The most recent mapping completed by Noricum has delineated three, north dipping, ore horizons. The southernmost mineralised horizon is well exposed laterally for 4km between the valley floor (835masl) and 1550masl. The northern mineralised horizon has less exposure at surface and can only be traced for 3km. The third horizon contains mainly carbonates and seems to be of less importance.
The ore minerals at Walchen are dominated by pyrite, with lesser amounts of the base metal sulphides chalcopyrite, galena and sphalerite. Pyrrhotite is present at deeper levels of the deposit. The average grade of the Walchen ore from 1942 was 1.71% Cu, 3.23% Zn, 2.48% Pb, 83g/t Ag, 0.5g/t Au. Recent assays have shown that pyrite and pyrrhotite can carry nickel and cobalt.
Historical exploration since the last cessation of mining has included an aerial geophysical survey utilising electromagnetic and radiometric methods was completed in 1980. The report detailing the survey mentions an anomaly at Walchen, and several other anomalies nearby, most are at relatively shallow depths.
In 1977 metallurgical test work focussing on floating and processing of the Walchen ore recommended the production of a Cu-Pb-Ag concentrate.
Local Geology
Walchen can be divided into a southern part, which is a zone of Wölzer mica schist, and a northern part, which is a zone of Ennstal phyllites. According to W. Fritsch (1953), the Walchen deposit is located 100m above the hangingwall of the lithological boundary.
The Wölzer mica schist belongs to the Middle Eastern Alpine Unit of the Muralpen Mountains and is represented as garnet mica schists with isolated graphite intercalations in the hangingwall. The age of this lithology might be Precambrian and has a general trend east west with a dip of 30deg – 70deg towards N.
The Ennstal phyllites are interpreted as the continuation of the higher metamorphic complex of the greywacke schist from the Palten Valley. Therefore, the Ennstal phyllites belong to the northern greywacke zone. The main lithologies of the Ennstal phyllite zone are sericite phyllites, quartzitic phyllites with intercalations of graphite phyllites, graphite quartzites and greenschists.
The boundary between Ennstal phyllites and Wölzer mica schist is along an acute E-W trend. The boundary consists predominantly of white sericite quartzite, bright/white, crumbly sericite phyllites, mica schist and phyllites. The thickness of the boundary varies considerably from around 50 m in the west to around 250 m in the mine area. The Walchen deposit is located within this boundary zone. If this boundary series is thin or missing the thickness of the mineralized horizon is affected.
Within the deposit and in the northern continuation of the deposit, also thick greenschist layers and a single hornblende schist layer occurs. Graphite schists occur in the footwall and between two ore horizons.
Ore and Gangue Minerals
The hangingwall of the mineralised horizon comprises bright sericite quartzite up to a thickness of 25m. The footwall of this sericite quartzite hosts the mineralization. The thickness of the mineralisation varies between 0.5 and 4.0m as does the sulphide content. Massive sulphide ore occurs mainly in the central part of the mineralised horizon, whereas disseminated sulphides occur above and below the massive sulphide ore.
The ore is of a complex composition with numerous metal sulphides in the massive and disseminated mineralisation. The ore minerals are fine-grained and intergrown, mainly pyrite, a smaller amount of chalcopyrite, galena, sphalerite, pyrrhotite (mainly at deeper levels), silver-bearing fahlore, arsenopyrite, antimonite, pyrargyrite, gudmundite; remobilized mineralisation that occurs as veins within the ore body might also contain valleriite.
The depth of oxidation of the ore zone is usually less than 3m and comprises azurite, malachite and large amounts of limonite.
The gangue consists of quartz, siderite/ankerite and calcite.
The old miners were mainly interested in chalcopyrite and the precious metals. According to a compilation of all available assays, an average copper content of 1.53% Cu was estimated. This is in accordance with the copper content of the roasted ore before 1924, which is 1.8 % Cu.
Lead and zinc are also present, the average lead content was 2.10% Pb and the average zinc content was 2.75% Zn. Arsenic content is low at 0.45% As.
Two different kinds of mineralisation occur at Walchen:
1. Horizon-like ore lenses, concordant within the sericite quartzite; consisting of massive and disseminated ore. In some parts, several sub-parallel lenses can join at depth. Horizons can be partially disrupted and deformed. The average vertical distance between the two main ore horizons is around 85m; the trend of the ore veins is approximately E-W.
1.1. The southern, lower ore horizon shows a thinning to the west, exposures prove an extension of approximately 4000m. The apparent thickness of the mineralisation on surface reaches up to 35m.
1.2. The northern, upper ore horizon is parallel to the southern ore horizon. The upper ore horizon is not as thick as the lower; showing an apparent thickness at the outcrop of up to 25m. The presence of the upper ore horizon was documented over a distance of 3000m.
1.3. The third ore horizon shows high contents in siderite and ankerite. It was found 120m above the upper main ore horizon. This horizon is referred to as “Karbonatgang” (carbonate vein).
2. The second type of mineralization consists of discordant veinlets that crosscut the primary ore body. These veinlets are considered as a remobilization of the ore that occurred during the Alpine orogeny.
The Company has published a Summary of Assays and Production Numbers from Historic Reports on its website. To view them, please go to www.noricumgold.com.
Ore Production and Calculations
Figures presented here have been taken from historical reports and should be treated as such, any reference to resource or reserve are not meant to infer JORC compliance.
Walchen was considered to be of limited interest after it was shut down in 1922 as only a small ore reserve remained that would have required a large investment. However support by Brigl u. Bergmeister (Niklasdorf/Leoben) in 1938 due to higher demand caused a reopening of the mine. During this work, no new drifts were made, but only a restoration of the existing drifts.
Studies performed by the geological survey in Vienna in 1940 did show interest for reopening the mine. More extensive work started in 1942 and was successfully performed until 1945.
A report made at the closing of the operation (Kupferer ,1922) mentioned non JORC proven ore reserves of approximately 50,000 tonnes; whereas in 1945 (after the exploration work stopped), the Studiengesellschaft Deutscher Kupferbergbau mentioned non JORC proven and probable ore reserves of 423,470 tonnes; this number was considered as correct (J. Jungwirth, 1948).
The continuation of the work after the end of the war by the company Brigl u. Bergmeister did not lead to mine becoming operational. Mining at Oeblarn has a long history where ore bodies were mined more or less extensive for nearly 400 years. The extension of the ore bodies towards depth is still not known but seems probable.
The total production between 1680 and 1858, according to information by K. A. REDLICH (1903) was:
-- Copper (metal) 3,585.656 t -- Sulphur 1,149.523 t -- Gold 0.055 t -- Silver 1.978 t -- Lead 4.200 t
According to old calculations, 56 – 78 t of copper was produced annually between 1706 and 1715. Production figures from 1824 and 1842:
1824 1842 Gold 33.918 kg 1.671 kg Silver 2,550.654 kg 162.431 kg Copper 406.280 t 23.464 t Sulphur 228.088 t 13.300 t Vitriol 225.652 t 28.504 t
These calculations provide a strengthened understanding of the Project thereby providing a strong rationale for continued exploration.
