- Larvikite
Larvikite is probably a type of
syenite , notable for the presence of handsome, thumbnail-sized crystals of feldspar, which are multiply-twinned on the micro-scale and shot through with small inclusions, giving its characteristic silver blue sheen (Schiller effect) on polished surfaces.Olivine can be present along withapatite , but there is rarely any freequartz . Usually titanium rich, with titanaugite and/or titanomagnetite present.The name originates from the town of
Larvik inNorway , where this type of igneous rock is found.This rock is very popular in the High Street in the UK, for its high polish and spectacular reflections from its feldspars and is frequently found fronting the facades of banks. It is sometimes known informally as "Blue
Granite ", although almost nothing of its mineralogical composition makes it granitic.External links
* [http://home.c2i.net/aolarsen/Osloregion.htm The Larvik Plutonic Complex]
* [http://www.cst.cmich.edu/users/dietr1rv/larvikite.htm R. V. Dietrich, 2006, Gemrocks]
* [http://www.nhm.uio.no/geomus/nettutstillinger/Osloriften/larvikitt-eng.html Larvikite - University of Oslo Geological Museum]
* [http://petrology.oxfordjournals.org/cgi/content/abstract/21/3/499 Petrogenesis of the Oslo Region Larvikites and Associated Rocks (abstract)] Journal of Petrology, 1980, volume 21, Number 3, pages 499-531
* [http://www.springerlink.com/content/q6hp62816627x286/ Structure of the larvikite-lardalite complex, Oslo-region, Norway, and its evolution (abstract)] International Journal of Earth Sciences, 1978, volume 67, number 1, pages 330-342
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