Linhorka Hill, Staré, Třebívlice, Litoměřice District, Ústí nad Labem Region, Czech Republici

Regional Level Types
Linhorka Hill	Hill
Staré	Village
Třebívlice	Municipality
Litoměřice District	District
Ústí nad Labem Region	Region
Czech Republic	Country

Outcrops of a Tertiary basalt tuff breccia at Linorka hill. In the tuff-breccia, different types of xenoliths occur (sandstone, gneiss as well as serpentinised and garnetiferous peridotite, dunite, lherzolite, and eclogite).

Linhorka is an indistinct hill in the cadastral territory of the village of Staré, which is an administrative part of the village of Třebívlice in the district of Litoměřice in the Ústí nad Labem Region. Linhorka, which is located in the Protected Landscape Area of ​​the Czech Central Mountains, is a geological and mineralogical locality of national importance.

Linhorka is located in the western part of the Milešov Central Highlands, which is a geomorphological subunit of the Czech Central Highlands. At the eastern foot of Linhorka, the local meadows and overgrown orchards border the buildings of the village of Staré, on the western side, the village of Leská, which is also part of the village of Třebívlice, adjoins the hill. The forested steeper northeastern side of the hill is bordered by the Kuzovské brook, on some newer maps known as Žejdlík, but more commonly known (also in older documentation) as Granátka.

Linhorka is a remnant of a Tertiary maar-type volcano.

As in the case of some other hills in this area (e.g. Baba u Děčan, Granátový vrch or Bota u Měrunic, Svinky u Kozlů, Syslík and Malý vrch u Třtěna), it is a diatreme, i.e. a volcanic inlet path filled with basalt breccia, containing fragments of pyrope-bearing rocks — serpentinised peridotites — dragged by a volcanic explosion from the depths of the Earth.

The age of the garnets (pyropes) brought to the surface by the maar's explosion, about 10 million years ago, is at least 340 million years. The surroundings of the maar were formed by softer Mesolithic rocks, subject to faster weathering, which also accelerated the erosion and weathering of the maar, which was originally about 300 meters higher than the current highest point of Linhorka. Chimney breccia rocks, even with pyropes, which are very hard and resistant to weathering, were spread around and deposited in the Quaternary gravels along the southern peaks of the Bohemian Central Mountains.

While only pyropes occur in the parent rock on Linhorka, numerous other minerals can be found in the alluvium of the Kuzovské brook, such as moissanite, zircon, apatite, ilmenite, spinel, picotite, chromium diopside, disthene (kyanite) or sapphire, but always only small grains up to two millimetres. In the past, three small diamonds have also been found in the southern foothills of the Bohemian Central Mountains.

The first written mention of the mining of Czech garnets is contained in the book De natura fossilium by Georgius Argricola from 1546, but in reality, pyropes were obtained in Bohemia much earlier, as evidenced by their occurrence in older jewellery. In the oldest period, it was probably only a surface collection, mentions of digging and mining garnets appear only during the reign (1576–1612) of Emperor Rudolf II (18 July 1552 – 20 January 1612).

In the 19th century, the rock containing pyropes was mined in Linhorka by smaller shafts. In the 1960s, a geological survey was conducted on Linhorka to search for diamond-bearing structures similar to South African kimberlites. No kimberlites were found here, but detailed information was obtained about the local diatreme and its tubular shape.

At present, only the extraction of garnets from Pleistocene strips of pyrope-bearing gravels is considered promising and economically efficient. Based on surveys, it was possible to identify three deposits, referred to as Podsedický, Chrášťany and Třebivlice, while the primary source of pyropes in all these cases is Linhorka.

Other Databases

Wikipedia:	https://cs.wikipedia.org/wiki/Linhorka
Wikidata ID:	Q57313906

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References