Fenite
“Altered by alkaline magma”
Fenite is a metasomatic rock that forms when country rock is chemically altered by hot, alkali-rich fluids emanating from carbonatite or nepheline syenite intrusions. The process, called fenitization, transforms ordinary rock into a sodium- and potassium-enriched assemblage.
alkali feldspar, aegirine, alkali amphibole, nepheline, calcite
Fen Complex (Norway), Alnö (Sweden), Phalaborwa (South Africa), Kaiserstuhl (Germany), Jacupiranga (Brazil)
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Fenite is named after the Fen Complex in Norway, where the process was first described — it's also the same location that gave 'fenite' and 'fenitization' to geological vocabulary.
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