Grube Wolf, Herdorf, Siegerland, Rheinland-Pfalz, Deutschland
The Wolf mine belongs to the
Siegerland siderite district where mining goes back to celtic times. The ore of this district is primarily of sideritic type with more or less developed oxidation zones where limonite/goethite is prevalent. Also Pb, Zn, Cu and Ag as well as Co and Ni minerals occurred frequently - especially at the upper levels - and mostly have been mined at the beginning of modern mining. Mineralization is of hydrothermal origin and developed as veins in Devonian sedimentary rocks (shales, sand- and siltstone) of the Rheinisches Schiefergebirge. The Wolf mine was characterized by a deeply developed oxidation zone (to a depth of almost 400 m), probably due to the influence of the intrusion of tertiary basaltic melts in the neighborhood which provided thermal energy and fluid flow favouring the alteration of the siderite veins. The rhodochrosite finds were restricted to the limonitic ores of the oxidation zone. Towards depth the ore became sideritic with quartz gangue and towards the roots of the veins the quartz content increased.
The Wolf mine is one of the younger mines of the district. Mining started about 1870 when limonite ore was extracted via adits. In 1890 the Reifenrath brothers from Neunkirchen acquired the mine and sank a shaft. Having reached a depth of 300 m the mine was sold in 1917 to Krupp, Essen and modernized by the installation of new steam machines for haulage. The water pumps were fitted with electric power supply. Consequently the extraction tonnage increased to 4,000 - 5,000 tonnes per month. During the 1920s 200 to 250 miners worked at the mine. In 1925 the mining stopped due to economic reasons. The surface installations were demolished and the mine was flooded. 10 years later the reopening was prepared by pumping out the mine and the building of new surface installations including an electric hauling machine and a cableway to transport the ore to the central processing plant at the Füsseberg mine in Daaden-Biersdorf. On 1st of may 1937 the mine was then reopened again. With an extraction of 84,000 tonnes of ore the year 1944 marks the best yield in the history of the mine. But in 1945 the mine closed again due to World War II impact and the mine was flooded again. In 1953/54 the last mining period at the Wolf mine started: it then was consolidated with the San Fernando, Friedrich-Wilhelm, Füsseberg and Große Burg mines to a combined mining complex. The mined ore was transported underground to the San Fernando mine and hauled and processed there. Finally in 1962 the mine was completely closed.
Rhodochrosite from the
Wolf mine is probably one of the best known mineral species from Germany in the world. The specimens from there are considered to be the best of Europe and they are present in museums and collections worldwide. Finds were restricted to the active mining period so nowadays specimens from there are highly sought after and increasing in value.
The rhodochrosite varies in colour from salmon pinkish to raspberry pink or orange-reddish to brownish. Typically it is associated with limonitic matrix where it forms crystals and aggregates in vugs of the ore. The habit varies from single millet-seed shaped crystals to star or hedgehog shaped aggregates of those, barrel and cone shaped crystals as well as sheave-like aggregates. Most of the crystals are built by numerous small steep scalenohedral subindividues. The crystals reach up to about 2 cm size, larger crystals have been extremely rare. The majority of the crystallized samples show crystal sizes from a few mm to about 1 cm. Also botroydal and spherical aggregates and coatings were common. The aggregates often show a 'raspberry' like habit ('Himbeerspat' - raspberry spar - Breithaupt, 1832). The most beautiful specimens are of a deep orange-pink colour, they are translucent and provide a great contrast to the limonite matrix. Combo specimens of rhodochrosite with malachite-coated crystals of native copper (reaching sizes of up to about 3 cm) on matrix are the most interesting association of the Wolf mine. The best and richest specimens were found in a zone around the 350 m level.
References
- A. Hoffmann (1964): Beschreibung rheinland-pfälzischer Bergamtsbezirke - Band 1 Bergamtsbezirk Betzdorf. - Verlag Glückauf, Essen.
- H.-G. Koch (1982): Erzväter - Berg- und Hüttenleute im Siegerland und Westerwald. - Verlag Gudrun Koch, Siegen.
- W. Richartz (1979): Rhodochrosit von der Grube Wolf. - LAPIS, Vol. 4, Nr. 10, 12-16.
- R. Bode (1980): Die Grube Wolf in Herdorf, Siegerland. - Emser Hefte 3, 6-35.
- M. Reinhardt, J.M. Henrich (2005): Die Grube Wolf in Herdorf. - Mineralien-Welt 16 (5), 14-37.
Mineral List
20 entries listed. 19 valid minerals.
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