Abandoned Dobsina mines - the Floss Ferri Heaven

Author: Zbyněk Buřival
Views: 3778

The Dobsina area was probably inhabitated by Slavic tribes in prehistoric times. Historic documentation begins with an invitation to German miners in 1326 but it's likely that mining started much earlier.


The early spring landscape near the Dobsina town.

Historic mining

The first interesting products of the area were iron and copper, mined first from the weathered outcrops and later from ore veins underground. Mining of copper ores has decreased since the 19th century and finally came to the end in 1919. The iron mines remained very productive for centuries, making Dobsina town an important producer of iron and steel. The 18th century saw the use of big open pits for extracting siderite and iron was mined continuously until 1970.


Abandoned adits and shafts of historic Dobsina mines are still open to crazy explorers.
The ghost of Albert Russ will be a guide to the Dobsina underground mines.

Cobalt and nickel ores had been mined since 1780: for a few decades Dobsina was the biggest producer in the world. However, 1875 saw the discover of new, bigger deposits overseas, and in 1897 mining of cobalt and nickel in Dobsina came to a halt. Mercury, bismuth and arsenic were mined for a short periods during 18th and 19th century.


Great example of very delicate aragonite variety floss ferri in its natural environment.

Geological settings

The Dobsina area occupies the border zone between the Gemericum and Veporicum unit. Its structure has been vastly complicated by numerous tectonic events. Simply put: the oldest part of the unit is paleosoic, built by metavolcanic rocks with intrusions of gabbro-diorites and diorites. On these rocks, sedimentation of basal conglomerates and later various sandstones, limestones and dolomites occurred. These sediments are late Paleosoic to Mesosoic age. Some of the dolomites have been metasomatically changed into huge deposits of ankerite and siderite. The whole area was at some point tectonically sheared, leading to the formation of multistage hydrothermal veins.


Layers and stalactites of aragonite form when carbonate rich waters enter the open space of the old adits. The small amount of cobalt can turn the aragonite into the blue variety called zeiringite.

Most of the ore veins are composed of quartz, ankerite, siderite, chalcopyrite and tetraedrite. Less common - but very important - are ore veins which include skutterudite, Ni-skutterudite and gersdorffite. Other sulfides included, among many others, less common arsenopyrite, nickeline, pararammelsbergite. Most interesting among the rare minerals are aikinite, native bismuth, krupkaite, bismuthinite or krutovite.


Some parts of the mine are already almost fully turned into the aragonite karst caves with typical karst features.
The water flow from the upper levels of the mine created this beautiful aragonite cascade.

But what makes Dobsina very interesting is aragonite - floss ferri. Some abandoned adits still drain significant amount of water and, as many ore veins and nearby rocks are rich in carbonates, some karst features have evolved inside the old mines. Some parts of the old adits are fully coated with aragonite layers, roofs are full of stalactites and walls are decorated with abundant floss ferri aggregates. Some aragonites are even colored blue or pink by Ni-Co ores.




Aragonite adits of Dobsina

I was very fortunate to visit an abandoned aragonite-rich adit in Dobsina with Albert Russ. We spent three days photographing the floss ferri in its natural environment, a task which is often quite challenging. The abandoned mine has really awesome parts fully covered by aragonite and full of stalactites, cave pearls, small ponds and other typical karst features. We also found some nice areas with bright blue aragonite, one place also had interesting blue-pink color patterns.


Albert Russ working on his awesome pictures. Creating macrophotos in the underground mine is trully an extreme photography.

Despite the secrecy of this place, some parts were unfortunately already damaged by collectors. We collected samples from the collapsed or damaged walls. There is no reason to chisel a hole into the nice aragonite layers or floss ferri bushes. Most floss ferri pieces are so delicate that it is almost impossible to recover them anyway. Because of potential for further damage, we will not reveal the location of this particular beauty. The mine can collapse any time or it can grow into even more beautiful place in the next years.




Even the regular looking stalactites can grow inside the abandoned mines.
Karst features are well developed in some parts of the mine.
Usually very rare cave pearls are quite abundant in Dobsina mines. However, they are formed by different process then normal karst cave pearls.

Comments

Charles 28.11.2015 21:49:20

Great story about the thrill of visiting an abandoned mine. Have been to Europe many time for business, not for rockhounding however but would love to include that in the next trip. Sounds like they are accessible, like you said, to "crazy explorers" which is awesome.