Active open-pit gold mine at Ada Tepe, south of Krumovgrad, on the site of Europe's oldest known gold workings.
The Ada Tepe gold deposit, located approximately three kilometres south of Krumovgrad in the Eastern Rhodopes of south-eastern Bulgaria, occupies a hill that was exploited for gold as far back as the Late Bronze Age, making it the oldest known gold mine in Europe. Modern development of the deposit began after Dundee Precious Metals' indirect subsidiary Balkan Mineral and Mining AD secured an exploration licence in June 2000. Following extensive environmental permitting, the Bulgarian Council of Ministers granted a 30-year concession in February 2011.
Construction commenced in the fourth quarter of 2016, and first gold was produced in March 2019. Commercial production was declared in June 2019, with formal operating permits received in August of that year. The deposit contains a low-sulphidation epithermal gold-silver orebody estimated at 807,000 oz of gold grading 4.04 g/t Au.
The mine operates by conventional open-pit methods using hydraulic excavators and haul trucks, with ore processed through a crushing, grinding, and flotation circuit. The mine life plan extended through 2026.
The Ada Tepe hill, rising to 495 metres approximately three kilometres south of Krumovgrad in the Eastern Rhodopes of south-eastern Bulgaria, was the site of gold extraction from approximately 1500 BC to around 600 BC during the Late Bronze Age and Early Iron Age. Archaeological investigations beginning in 2005, and a major project launched by the Bulgarian Academy of Sciences in 2010, established Ada Tepe as the oldest known open-pit gold mine in Europe. The Thracian miners exploited quartz veins using wooden and fire-setting techniques; experimental work conducted at the site demonstrated that 350 kg of ore processed by ancient methods yielded approximately 30 grams of gold. The gold was mined from a low-sulphidation epithermal deposit of unusual geological character, hosted in Maastrichtian-Paleocene sedimentary rocks above a detachment fault contact with underlying Paleozoic metamorphic basement, within the Eastern Rhodopes metamorphic core complex.
Modern prospecting interest in the Eastern Rhodopes revived during the 1930s under Italian survey activity, and German-funded mining operations in the wider Rhodopes region were contracted in 1939 during the Second World War, though Ada Tepe itself was not among the principal targets of that era. The Rhodopes more broadly became a significant lead, zinc, and gold producing region under socialist Bulgaria, with state enterprise GORUBSO operating multiple mines across the mountains from the 1960s onward. The specific Ada Tepe deposit was not brought into modern industrial exploitation until the post-socialist period.
In June 2000, Balkan Mineral and Mining AD, an indirect subsidiary of the Canadian company Dundee Precious Metals Inc., secured an exploration licence covering 130 km2 of the Krumovgrad goldfield. The licence area was subsequently reduced to 100 km2 in accordance with the Underground Resources Act of 1999. Dundee Precious Metals acquired its interest in the project in 2003, paying approximately USD 26 million for the concession rights. The company spent the following fifteen years navigating environmental permitting and community engagement, including the development of the Integrated Mine Waste Facility, described as the first of its kind in Europe. Significant public opposition arose during the permitting process, with approximately 10,000 signatures collected against the project in the municipality of Krumovgrad, and concerns raised by communities and authorities in neighbouring areas of Greece and Turkey regarding potential contamination of the Maritsa river system.
The Bulgarian Council of Ministers approved development and granted a 30-year concession in February 2011. Following further engineering and environmental work, the final construction permit was issued in August 2016. Construction commenced in the fourth quarter of 2016, with Amec Foster Wheeler Australia engaged as lead designer and engineering procurement construction contractor. Steel structures installation began in December 2017. First gold was produced in March 2019, and commercial production was formally declared in June 2019. Annual gold production guidance for the initial ramp-up year was set at between 45,000 and 60,000 ounces. Formal operating permits from Bulgarian authorities were received on 30 August 2019.
The Ada Tepe deposit is classified as a high-grade, low-sulphidation epithermal gold-silver deposit. Mineral reserves were estimated at approximately 6.2 million tonnes grading 4.04 g/t Au, containing approximately 807,000 oz of gold, with the revised life-of-mine plan of January 2023 recording an average grade of 5.19 g/t Au. The mine operates by conventional open-pit methods, employing drilling and blasting followed by loading with hydraulic excavators and 40-tonne haul trucks. The processing plant treats ore through crushing, single-stage semi-autogenous grinding, and flotation to produce a gold concentrate. Process water is purified to drinking quality before discharge to the Krumovitsa River. The mine is owned and operated by Dundee Precious Metals Krumovgrad EAD, a wholly-owned indirect subsidiary of Dundee Precious Metals Inc.
Since commencing operations, Ada Tepe delivered consistent quarterly performance, with the updated life-of-mine plan of January 2023 projecting production through 2026 with approximately 66,000 additional ounces of recovered gold relative to the preceding 2020 plan, at an average grade of 5.19 g/t. Visitor centres at Ada Tepe provide interpretive exhibits on the ancient Thracian mining history of the hill. Plans for restoration of the archaeological heritage of the site were associated with proposals for an open-air museum dedicated to ancient mining and metallurgy. The modern mine is located within the Natura 2000 biodiversity zone.