Sodicgedrite, Orthopyroxene Subgroup, Rutile

This is the first find of the UHT granulite facies orthoamphibole Sodicgedrite in Bamble, Norway. It occurs as beige colored inclusions up to 10 mm in an Al-rich orthopyroxene and contains between 2.68 to 3.04 wt% Na2O. It is also high in Ti (1.02-1.04 wt% TiO2) and Al (18.8-20.0 wt% Al2O3). From a Garnet-Sillimanite-Spinel-Orthopyroxene granulite. Collected in 1986.

Sodicgedrite has recently (2009) been identified as an indicator mineral for Ultra High Temperature(UHT)granulite facies metamorphism of Mg-Al rich metapelites in India and Antarctica (1). Similar UHT granulite conditions have recently also been reported for the first time from a locality close to Ærøya, Bamble-sector (2).

1. Kanazawa et al. 2009: The stability and origin of sodicgedrite in ultrahigh-temperature Mg-Al granulites: a case study from the Gondwana suture in southern India, Contrib Mineral Petrol (2009) 157:95–110

2. Kihle et al., 2010: Epitaxial quartz inclusions in corundum from a sapphirine–garnet boudin, Bamble Sector, SE Norway: SiO2–Al2O3 miscibility at high P–T dry granulite facies conditions, Journal of Metamorphic Geology, Volume 28, Issue 7, pages 769–784, September 2010

Collection: J Kihle

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Photo added: 2nd Feb 2010