Almond (mineralogy)
A almond (engl. Amygdule or amygdale ) is a fully with mineral filled substance former cavity ( Geode ) in volcanic rocks . The rock surrounding the almonds is accordingly referred to as almond stone . Cavities that are incompletely filled with mineral substance, on the other hand, are referred to as drusen , although the terms geode, druse and almond are rarely correctly delimited in common parlance, but are often used synonymously in a misleading manner.
The name refers to the shape of the fruit of the almond tree , as the gas bubbles trapped in the flowing lava flow take on a similar shape when geodes are formed.
The term almond is particularly frequently used in connection with the formation of agates , the microcrystalline variety of the mineral quartz , as this is preferably formed as a cavity filling in almond stones.
literature
- Rudolf Graubner: Lexicon of geology, minerals and rocks . Emil Vollmer Verlag GmbH, Munich 1980, ISBN 3-87876-327-1 , p. 231 .
- Martin Okrusch, Siegfried Matthes: Mineralogy: An introduction to special mineralogy, petrology and deposit science . 7th edition. Springer Verlag, Berlin, Heidelberg, New York 2005, ISBN 3-540-23812-3 , pp. 11.172 .
- 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: Christian Weise (ed.): ExtraLapis . tape 19 . Christian Weise Verlag, 2000, ISBN 3-921656-54-0 , ISSN 0945-8492 .
Web links
Individual evidence
- ^ Ron Vernon: A practical guide to Rock Microstructure . Cambridge University Press, Cambridge 2004, ISBN 978-0-521-89133-2 , pp. 475 .