Nuummit

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Nuumit , also Nuummit , is a rare metamorphic rock, which consists mainly of the minerals gedrit and anthophyllite . The name is derived from the location Nuuk in Greenland .

rock

The basic color is almost black and often shimmering in color due to inclusions; the rock is opaque. In addition to the two amphiboles, gedrite and anthophyllite, pyrite , pyrrhotite and chalcopyrite occur as secondary mixtures. The two amphiboles form a twin lamellae, which was created by segregation (exsolution) in the solid state, and is characterized in polished specimens by a yellowish-gold iridescence .

The originally igneous rock was subject to at least two metamorphic events after its formation in the Archean around 2.8 Ga (billion years ago) geologically a short time later - by around 2.7 Ga and 2.5 Ga - and is now an ortho- amphibolite to address.

Occurrence

The rock was first collected in Greenland in 1810 by the mineralogist KL Giesecke and first described scientifically in 1905 and 1924 by OB Bøggild. Nuumit has also been found in Finland , the United States, and the Commonwealth of Independent States .

Nuumit is rare and, due to its iridescence, sought after by gem dealers. It is a rough stone or tumbled stone placed on the market. The rock is in demand by collectors and in esotericism .

literature

  • Peter W. Uitterdijk Appel, Aage Jensen: A New Gem Material from Greenland: Iridescent Orthoamphibole [nuummite]. tape 23 , no. 1 , April 1987, ISSN  0016-626X , pp. 36-42 ( gia.edu ).
  • PE Champness, KA Rodgers: The origin of iridescence in anthophyllite-gedrite from Simiuttat, Nuuk district, southern West Greenland . In: Mineralogical Magazine . tape 64 , no. 5 , October 1, 2000, pp. 885-889 , doi : 10.1180 / 002646100549715 .
  • KA Rodgers, et al .: Iridescent anthophyllite-gedrite from Simiuttat, Nuuk district, southern West Greenland. Composition, exsolution, age. Mineralogical Magazine, Volume 60, No. 6, pp. 937-947, December 1996 ( abstract )
  • K. Secher, P. Appel: Gemstones of Greenland - Exploration and Mining in Greenland. Geology and Ore, No. 7, January 2007, p. 9.

Individual evidence

  1. ^ Minerals in Greenland . In: Geological Survey of Denmark and Greenland [GEUS] (Ed.): Geology and Ore . No. 12 , 2008, p. 12 ( geus.dk [PDF; 4.7 MB ]). geus.dk ( Memento of the original from December 21, 2011 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  @1@ 2Template: Webachiv / IABot / www.geus.dk
  2. ^ Secher and Appel 2007.
  3. ↑ Champness and Rodgers 2000, p. 885.

Web links