| 词条 | Nuummite |
| 释义 |
| name = Nuummite | category = Mineral variety | image = File:Nuummite-001B.jpg | image_caption = | imagesize = | caption = | formula = ({{chem|Mg|2}})({{chem|Mg|5}}){{chem|Si|8|O|22}}{{chem|(OH)|2}} | molweight = 780.82 gm | color = Black, grey | habit = | system = | twinning = None | cleavage = Perfect on 210 | fracture = Conchoidal | mohs = 5.5 - 6.0 | luster = Vitreous/glossy | refractive = 1.598 - 1.697 Biaxial | opticalprop = | birefringence = 0.0170 - 0.230 | pleochroism = | streak = | gravity = | density = 2.85 - 3.57 | melt = | fusibility = | diagnostic = | solubility = | diaphaneity = opaque | other = }}Nuummite is a rare metamorphic rock that consists of the amphibole minerals gedrite and anthophyllite. It is named after the area of Nuuk in Greenland, where it was found.[1][2][3] DescriptionNuummite is usually black in colour and opaque. It consists of two amphiboles, gedrite and anthophyllite, which form exsolution lamellae that give the rock its typical iridescence. Other common minerals in the rock are pyrite, pyrrhotite and chalcopyrite, which form shimmering yellow bands in polished specimens. In Greenland the rock was formed by two consecutive metamorphic overprints of an originally igneous rock.[3] The intrusion took place in the Archean around 2800 million years ago and the metamorphic overprint was dated at 2700 and 2500 million years ago.{{citation needed|date=December 2012}} HistoryThe rock was first discovered in 1810 in Greenland by the mineralogist K. L. Giesecke.[4] It was defined scientifically by O. B. Bøggild between 1905 and 1924.[5] True Nuummite is only found in Greenland. Due to its iridescent nature, this rare stone is sought after by gemstone dealers, collectors and those interested in the esoteric. It is often sold with tumble finishing. References1. ^{{citation|editor-surname1=Geological Survey of Denmark and Greenland (GEUS)|periodical=Geology and Ore|title=Minerals in Greenland |issue=12|pages=12|date= 2008|language=German|url=http://www.geus.dk/minex/go12.pdf}} 2. ^{{cite web|title=Nuumite|url=http://www.classicgems.net/gem_nuummite.htm|publisher=ClassicGems.net|accessdate=1 December 2012}} 3. ^1 {{cite web|title=Gemstones of Greenland|url=http://www.geus.dk/minex/go07.pdf|accessdate=4 December 2012|work=Geology and Ore|issue=7|date=January 2007|publisher=Geological Survey of Denmark and Greenland (GEUS)}} 4. ^{{cite journal|author=K. Secher & P. Appel|title=Gemstones of Greenland - Exploration and Mining in Greenland.|journal=Geology and Ore|date=January 2007|volume=7|url=http://www.geus.dk/minex/go07-uk.htm|accessdate=8 November 2012|page=9}} 5. ^{{cite journal|author=P. E. Champness, K. A. Rodgers|title=The origin of iridescence in anthophyllite-gedrite from Simiuttat, Nuuk district, southern West Greenland.|journal=Mineralogical Magazine|date=October 2000|volume=64|issue=5.1|pages=885–889|url=http://www.ingentaconnect.com/content/minsoc/mag/2000/00000064/00000005/art00010|accessdate=8 November 2012|doi=10.1180/002646100549715}} Further reading
2 : Gemstones|Metamorphic rocks |
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