Snow head globe

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Fragment of a snow head globe, Oberhof

Snow-head spheres (scientifically lithophyses ) are mineral-filled rock cavities ( drusen ) that can be found in Thuringia. The stones owe their name to their main location, as they occur around the Schneekopf near Gehlberg , in the middle of the Thuringian Forest . Formations of the same origin are known from many places where volcanic rocks occur, for example around Idar-Oberstein in Rhineland-Palatinate .

Structure and shape

The snow head globe is a spherical or spheroidal stone structure. Usually it is found in the form of a sphere, but it can also appear in a split form. The snow head spheres are usually completely filled with agate , chalcedony or quartz crystals . Every now and then there are approaches of jasper or amethyst . It is not uncommon for hematite or fluorite crystals to grow on it . The mineral filling often shows a geopetal structure .

The spheres, measuring between a few centimeters and up to two meters, occur in volcanic effluent rock such as porphyry or porphyrite. The outer shell of the balls is usually made of porphyry. The porphyry base that surrounds the snow head balls is much softer than the inside of the balls. As a result, this outer shell weathers faster, so that the contents are exposed.

The snow head spheres were formed in the Permian about 250 million years ago through the formation of gas bubbles in the lava mass . In the cavities created by the gas bubbles, the crystals later crystallized through precipitation from mineralized water.

literature

  • Ursel Laarmann, Michael Landmesser, Maximilian Glas, Rupert Hochleitner, Rudolf Dröschel, Peter Jeckel: Agate: The precious stone from which Idar-Oberstein was created: history, origin, finds . In: Lawrence H. Conklin (Ed.): ExtraLapis . tape 19 . Christian Weise Verlag, 2000, ISBN 3-921656-54-0 , ISSN  0945-8492 , p. 26th f . (Explanation of the formation of drusen).

Web links

  • Snow head globe. Entry in the Mineralienatlas Wiki
  • Snow head globe. Private homepage of the collector Frank Möller with further information and photos of snow head balls