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Ijolite (Oka Carbonatite Complex, Early Cretaceous, 124-125 Ma; Oka Niobium Mine, Quebec, Canada)

Ijolite is an igneous rock consisting essentially of nepheline and augite.[1] Ijolite is a rare rock type of considerable importance from a mineralogical and petrological standpoint. The word is derived from the first syllable of the Finnish words such as Iivaara, Iijoki · and Ii, all geographical names in Finland, and the Ancient Greek Xiflos, a stone. Ijolite occurs in various parts of the Kainuu region of eastern Finland and in the Kola Peninsula of northwest Russia on the shores of the White Sea.[2] Ijolite was first defined and named by Finnish geologist Wilhelm Ramsay.[3]

The pyroxene is morphic[clarify], yellow or green, and is surrounded by formless areas of nepheline. The accessory minerals are apatite, cancrinite, calcite, titanite and schorlomite, a dark-brown titaniferous variety of melanite-garnet. This rock is the plutonic and holo-crystalline analogue of the nephelinites -volcanic equivalent and nepheline-dolerites; it bears the same relation to them as the nepheline syenites have to the phonolites.[2]

A leucite-augite rock, resembling ijolite except in containing leucite in place of nepheline, is known to occur at Shonkin Creek, near Fort Benton, Montana, and was earlier called missourite,[2] but is now regarded as a variety of leucitite.[4]


  1. ^ Kresten, Peter; Troll, Valentin R. (2018). "The Alnö Carbonatite Complex, Central Sweden". GeoGuide. doi:10.1007/978-3-319-90224-1. ISBN 978-3-319-90223-4. ISSN 2364-6497. S2CID 135266142.
  2. ^ a b c Chisholm 1911.
  3. ^ Lindberg, Johan (January 19, 2011). "Ramsay, Wilhelm". Uppslagsverket Finland (in Swedish). Retrieved November 30, 2017.
  4. ^ Gupta, A.K and Yagi, K. (1980). Petrology and Genesis of Leucite-Bearing Rocks. Berlin: Springer-Verlag. ISBN 978-3-642-67552-2.{{cite book}}: CS1 maint: multiple names: authors list (link)