EMED Mining's activities in Slovakia is concentrated on a cluster of volcanic features in the central part of the country, where the Company is exploring for gold and associated minerals in its 100%-owned Detva, Banska Stiavnica-Hodrusa-Hamre and Velke Pole licences. Each is examined below.
The Detva licence area is located 25 km to the east of the Stiavnica-Hodrusa district. The geology consists of a caldera-graben complex in the centre of a large stratovolcano. Widespread propylitic and localised advanced argillic alteration in the area indicates substantial hydrothermal activity. This setting is considered to be a classic geological environment for the formation of large porphyry gold orebodies.
In October 2006, EMED Mining announced the discovery of the Biely Vrch porphyry gold deposit within the Detva licence. During 2008 the Company completed a diamond drilling program of 34 holes on a 100m by 100m grid pattern at Biely Vrch (Fig.1). Gold mineralisation was found to occur within a broad pipe-shaped quartz-veinlet stockwork zone associated with an andesitic porphyry intrusion. A number of drill cores were found to be mineralised over their entire length from surface to a depth of 300m.
The Biely Vrch drill program culminated in an initial JORC-standard preliminary Mineral Resource estimate prepared by Australian Mining Consultants (AMC) in 2009. Oxide and primary sulphide ore types were combined for a Mineral Resource estimate comprised of:
- Indicated: 17.7 million tonnes at 0.81g/t gold, containing 461,000 ounces
- Inferred: 24.0 million tonnes at 0.77g/t gold, containing 596,000 ounces
The Mineral Resource area measures approximately 350m north-south and 300m east-west and extends from surface to a depth of 250m. Mineralisation within the vertical pipe-shaped structure continues below this depth.
Using this preliminary mineral resource estimate, AMC prepared a preliminary economic assessment (scoping study) in 2010 that provided strong evidence of the potential value that developing the Biely Vrch deposit would create.
The scoping study indicated a positive base case economic profile for the development of an open-pit, heap-leach project. The key parameters are:
- Open-pit, heap-leach gold project
- Capital construction costs of $64 million
- Cash cost of production $529 per ounce
- Overall gold recoveries of 81%
- Production of 60,000 ounces of gold per year
- Mine life of more than 10 years
Behre Dolbear International reviewed the AMC Biely Vrch Mineral Resource estimate and scoping study in their NI 43-101 Technical Report on the Biely Vrch Gold Deposit (1.2MB pdf) dated 17 November 2010.
In 2011 two deep drill holes were executed at the Biely Vrch gold deposit. Both confirmed continuation of gold mineralisation in depth. Specifically DVE-51 and DVE-52 returned encouraging 761m and 783m at 0.62g/t and 0.84g/t, respectively, from surface, which is three times the depth of above reported resources.
In addition to Biely Vrch discovery, the Company has tested other gold porphyry targets since refining the relevant geological models and tools in 2007 within Detva and Company’s other licences. Eleven of those targets were tested, including drilling at five targets (Kralova, Slatinske Lazy, Zlatno and Sementlov). However, all of them were clearly of sub-economic grade. Other targets, such as Pila, Banisko, Skalka, Kalinka, Stozok and Podpolom, were rejected before drilling.
Biely Vrch gold deposit was given "exclusive deposit" status, which gives priority to the land being used for mining activities in September 2010, whilst a Protective Deposit Status was granted at the same year. In addition, EMED Slovakia, a 100%-owned subsidiary, was awarded a Corporate Authorisation for mining activities.
The District Mining Bureau (“DMB”) has designated a Mining Lease Area over Biely Vrch Gold Deposit in November 2012. The designation of a mining lease area over future open pit is a significant milestone on the permitting road map, although it is not a mining/operational permit. Following appeals by activists, the Central Mining Bureau (“CMB”) cancelled DMB’s decision and the case was returned to the DMB for re-decision in May 2013. As a result the permitting process has been suspended till the end 2016 by decision of the DMB in December 2013.
In September 2014 the Slovak Parliament adopted an amendment to the Mining Act by which cyanide leaching technology for gold processing in mining industry was totally banned.
Given EMED Mining’s focus on the restart of Proyecto Riotinto, which is progressing rapidly towards production, the Company decided to trade Biely Vrch Gold Resource to an investor, who could apply manpower and budget for its permitting and development. Currently, EMED is in communication with local and foreign investors, who demonstrated interest in this asset.
Banska Stiavnica-Hodrusa-Hamre Licence Area
The Banska Stiavnica-Hodrusa precious metals field is located some 35 km SW of EMED’s Biely Vrch project in Central Slovakia and is considered as the most mineralized area in the Central Slovakian Volcanic Field (CSVF). Historically this field has been mined for silver and gold from numerous north east trending epithermal veins extending over an area of 10km by 5 km. Estimated historical production (from the early Middle Ages to the present) is 2.4 million ounces of gold and 120 million ounces of silver.
EMED Mining has recognised a variety of styles and the potential for porphyry, skarn and stockwork styles of gold mineralisation that have not been investigated by previous explorers. In addition, EMED Mining has recognised areas of potential for high-sulphidation, epithermal style of gold mineralisation. This style commonly involves weakly anomalous in gold at surface, but can host extensive high-grade gold deposits at depth.
Early prospecting in 2006 tested potential for near-surface gold and silver mineralization at Banska Bela prospect. Six shallow drill holes totaling 447m were drilled through stock-work zone. Drilling intersected from 20-40m wide zones of quartz stock-work veinlets, limonite filled fractures, sulphides and silver bearing minerals in all 6 drill-holes. The results are interpreted that there has been significant supergene enrichment and dispersion of the gold mineralization around narrow 1-4m wide primary structures to a depth of approx. 20m – thus downgrading the potential for a near-surface, bulk-tonnage gold and silver resource on this particular vein structure.
At the same year, EMED has also investigated historically known magnetite skarn prospect Klokoc-Vyhne. Based on the poor gold results of verification drill-hole and re-assaying of the archive governmental drill-hole, EMED didn’t confirm previously reported intersection of 35m at 6.3g/t Au and therefore didn’t continue with further exploration at this prospect.
After the discovery of Biely Vrch gold porphyry at Detva license in 2006, EMED Mining commenced systematic exploration for gold porphyries in its licenses at CSVF including Banska Stiavnica-Hodrusa field. As a result three prospects (Zlatno, Sementov and Beluj) were drill-tested as porphyry targets by 8 drillholes totaling 1.6km. At all 3 prospects, porphyry mineralization was confirmed however drill intercepts didn’t reach economic values.
After completing a “porphyry stage” exploration within CSVF, EMED Mining returned back to the exploration for epithermal gold-silver rich vein system in prospective Banska Stiavnica-Hodrusa field. Priority drill targets have been identified following a review of data from the extensive historical mining records, recent data from the nearby Rozalia mine, as well as from the reconnaissance field work and sampling.
Rozalia mine is a small-scale underground operation, which exploits Au-rich epithermal veins discovered in late 80s of last century. This mineralization represents different mineralization event in comparison with steep narrow Ag-rich veins mined for centuries.
Four prospects were drilled totaling 1.8km. Three shallow holes at Quartzlager prospect examined historical workings for Rozalia style mineralization. One hole intercepted 5m at 5g/t Au eq. This result gives an indication of historical mining width and grades. Geochemistry confirmed that such grades are typical of the field epithermal veins which are mostly silver rich.
EMED has also started comprehensive digitization of archive maps aiming to create a 3D model of the entire mineral field, which could help better understand the spatial relationship between various mineralization styles and fluid deposition within this area.
Despite of numerous exploratory works and hundreds of years of intensive mining activity, Banska Stiavnica-Hodrusa mineral field remains highly prospective for gold/silver rich epithermal veins, since such geological settings in Slovakia are under-explored by modern exploration methods and advances in understanding of epithermal systems. In addition, this high grade mineralisation can be mined by underground mining methods and processing techniques that do not use cyanide, i.e. by gravity and flotation.
Velke Pole Licence Area
The current exploration license of Velke Pole covers an area of 47 sq. km. The initial exploratory works comprised geological mapping and sampling and focused primarily on porphyry type mineralisation. However, the licence comprises a historically important and prolific mining region including the Nova Bana Au-Ag epithermal deposit.
The Nova Bana deposit has a long mining history dated back to 13th century. It has been intensively mined in medieval times (with culminating operations in 14th and 15th centuries) down to the drainage level. Deeper parts of the deposit remain unexplored and thus they deserve further exploration.
EMED Mining’s exploratory works at Nova Bana started in 2010 and led into identification of drill targets. The initial drillhole NBVE-1, executed in 2011, failed reaching the target zone due to technical difficulties. Further drilling has not been undertaken, because of other priorities within EMED Group of Companies.
The Nova Bana prospect remains unexplored and constitutes an interesting focus for future exploration activities within the Central Slovakian Volcanic Field.
Given EMED Mining’s focus on the restart of Proyecto Riotinto, the Company has entered into a conditional Earn-in Agreement with Prospech Ltd, a private Australian exploration company, in relation to the exploration licences in the Hodrusa-Hamre-Banska Stiavnica and Velke Pole areas.
Prospech will invest up to a €1 million in return for an 81% interest in Slovenske Kovy, holder of the licences and EMED’s 100-owned subsidiary.
Information on the Company in Slovakian is available at www.emed-slovakia.com.