Madan, the Rhodope minerals

People have been taking lead out of this ground since the fifth century BC. Madan is an old ore-miners' settlement in the far south of Bulgaria, in the Yellow Share of the Rhodope Mountains.

What the miners follow is marble. The replacement orebodies sit in six marble horizons, some in place and some carried over by thrusting, each about four to five metres thick, within the Precambrian crystalline complex of the Rhodopean massif. The Madan dome is cut by Oligocene rhyolite dikes, and the host rocks logged for the district are amphibolite, gneiss and marble. Fluid inclusions put the ore-forming temperatures between 350 and 260 degrees Celsius.

The species list is what carried the name beyond the smelters. Galena and sphalerite are the ore, but the same ground has yielded rhodochrosite and rhodonite, fluorite, cerussite, barite, arsenopyrite, chalcopyrite, pyrite, marcasite, johannsenite, ilvaite, wollastonite, tennantite and tetrahedrite, and gold, among a good deal else.

The detail work is still going on. A study of the tennantite-tetrahedrite series from the Gradishte and Petrovitsa deposits found the two behaving quite differently: Gradishte samples are dominantly tennantite, while Petrovitsa crystals are exclusively tetrahedrite. Both are zincian varieties with low iron, and only the Petrovitsa material carries meaningful silver. The crystals show fine oscillatory zoning, and the textures place these fahlores late in the mineralising sequence.

The geography rewards the name-spotters. Petrovitsa is a peak on the Ardino Ridge at 1,309 metres, alongside Buchovitsa at 1,404 and Veternitsa at 1,372, so the deposits are named for the hills they sit under. The town runs down between the Arda and Varbitsa rivers and had about 6,600 people in 2019, most of them local Pomaks. There is a Madan Saddle on Smith Island in the South Shetlands named after the place, which is a long way to carry a mining town's name.