Železná hůrka (german: Eisenbühl) is an extinct

Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million years ...

volcano A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates are ...

and a national nature monument in the

Fichtel Mountains The Fichtel MountainsRandlesome, C. et al. (2011). ''Business Cultures in Europe'', 2nd ed., Routledge, Abingdon and New York, p. 52. . (german: Fichtelgebirge, cs, Smrčiny), form a small horseshoe-shaped mountain range in northeastern Bavaria ...

in the

Czech Republic The Czech Republic, or simply Czechia, is a landlocked country in Central Europe. Historically known as Bohemia, it is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the southeast. The ...

Location

Železná hůrka is located about 1 km south of Mýtina in the Lipová municipality, in Cheb District in the Karlovy Vary Region of the Czech Republic. It lies in the easternmost part of the

. The area has also other manifestations of volcanic activity. Another Quaternary volcano, Komorní hůrka, is located nearby. CO₂ outgassing occurs in the area.

Metallic iron

The name means "iron hill" in Czech. Fragments of metallic iron are found in the local basalt deposits. Iron usually occurs on Earth only in the oxidized form, as iron ore, and needs to be processed into metallic iron by

smelting Smelting is a process of applying heat to ore, to extract a base metal. It is a form of extractive metallurgy. It is used to extract many metals from their ores, including silver, iron, copper, and other base metals. Smelting uses heat and a ch ...

. It is thought that in the Železná hůrka area, iron-rich magma entered coal deposits which caused iron compounds to be reduced to metallic iron, in a process similar to

used by humans, but natural in origin. This kind of metallic iron from geological processes is rare on Earth (though it has been found in places including Disko Island).

Geology

Železná hůrka is a young volcano, geologically speaking. Samples from the lower, older part of its cone yielded the age of 519,000 years (with a margin of error of 51,000 years). Two samples from tephra deposits in nearby Mýtina (possibly related to the volcano's later activity) yielded the age of 300,000 years. The lower part of the volcanic cone consists of pyroclastic material deposited in discontinuous eruptions, with visible layering. At least the earliest of these eruptions were

phreatomagmatic Phreatomagmatic eruptions are volcanic eruptions resulting from interaction between magma and water. They differ from exclusively magmatic eruptions and phreatic eruptions. Unlike phreatic eruptions, the products of phreatomagmatic eruptions cont ...

, caused by contact of groundwater with hot magma; they deposited brownish layers of material which contains low-porosity hydroclasts, as well as fragments of the host rock (old rock crushed and carried away by the eruption) with oxidized surfaces. Then came another kind of volcanic (magmatic) activity, with less developed layering, which deposited black to dark-brown (melanephelinitic), slightly welded material, which contains fragments and blocks of porous lava, larger chunks of solidified lava known as volcanic bombs, and smaller fragments known as

lapilli Lapilli is a size classification of tephra, which is material that falls out of the air during a volcanic eruption or during some meteorite impacts. ''Lapilli'' (singular: ''lapillus'') is Latin for "little stones". By definition lapilli range f ...

Mýtina maar

A funnel-shaped dry depression, located less than two kilometres from Železná hůrka, was confirmed to be a volcanic

maar A maar is a broad, low-relief volcanic crater caused by a phreatomagmatic eruption (an explosion which occurs when groundwater comes into contact with hot lava or magma). A maar characteristically fills with water to form a relatively shallow ...

in 2008. This was the first maar discovered in Central Europe north of Alps and east of Volcanic Eifel.

References

{{Authority control Protected areas of the Czech Republic Cheb District