Druse (mineralogy)

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Aragonite (colorless) and kutnohorite (gray-brown) as a drusen filling in a carbonate geode
Agate almond with quartz gland

A druse is a former cavity ( geode ) in the rock that is incompletely filled with crystal collections of various types . Cavities that are completely filled with mineral substance are called almonds . The terms, which are often used synonymously, albeit misleadingly, are found mainly in connection with the description of agates .

The term gland is related to the medium high German words drusene , drusine , drusen for sediment (Hypo stasis), and can be up to the old German word Druos (plurality druosi , medium high German already drüese ) for gland or bump (also with tumor associated ulceration , abscess , node and boils ).

The so-called snow head spheres are a similar form of filled rock cavities .


The best-known sites of amethyst drusen are in South America, especially in the Brazilian state of Rio Grande do Sul , druses with lengths and volumes of several (cubic) meters have been and are repeatedly found. The currently largest is the Empress of Uruguay , a 3.27 meter high druse from Uruguay , which was exhibited in the American Museum of Natural History .

Druze can also be found in Germany, for example in the area around Idar-Oberstein or in the Ore Mountains . However, these rarely come close to the size and quality of the South American Druze.


Water with a high concentration of minerals seeps into cavities created by volcanic processes in the rock , which over time leads to the formation of crystals . The single crystals formed inside the geodesic spaces are younger, while the older generations often form crystalline shells. In the cavities of limestone there are limestone and brown sparrow drusen , in pebbles there are quartz drusen. Amethyst drusen appear as the innermost cladding of agates in melaphyr , zeolite drusen in volcanic rocks. The ore veins are also rich in druse formations .


  • Ursel Laarmann: The Gift of the Permian Volcanoes . How do the gemstones get into the volcanic rocks? In: Agate: The precious stone from which Idar-Oberstein was created: history, origin, finds (= Christian Weise [Hrsg.]: ExtraLapis . Volume 19 ). Christian Weise Verlag, 2000, ISBN 3-921656-54-0 , ISSN  0945-8492 , p. 26-27 .

Web links

Commons : Druse  - collection of images, videos and audio files

Individual evidence

  1. ^ Matthias Lexer : Middle High German Concise Dictionary 1966
  2. Hans Lüschen: The names of the stones. The mineral kingdom in the mirror of language . 2nd Edition. Ott Verlag, Thun 1979, ISBN 3-7225-6265-1 , p. 207 .
  3. Jürgen Martin: The 'Ulmer Wundarznei'. Introduction - text - glossary on a monument to German specialist prose from the 15th century (=  Würzburg medical historical research . Volume 52 ). Königshausen & Neumann, Würzburg 1991, ISBN 3-88479-801-4 , p. 125 , druos, drüese , drusene (also medical dissertation Würzburg 1990).
  4. The world's largest Amethyst geode - The 'Empress of Uruguay'. In: geologypage.com. January 11, 2017, accessed December 5, 2019 .
  5. 12-Foot Amethyst Geode Time Lapse. In: youtube.com. American Museum of Natural History, October 24, 2017; accessed December 5, 2019 .