A new occurrence of aegirine in Norway

The Hortavær Complex in north-central Norway is a well documented example of the formation of an alkaline magmatic suite due to the assimilation of carbonate and calc-silicate rocks (Vogt 1916; Gustavson & Prestvik, 1979; Barnes et al. 2003, 2005). In addition to calcic pyroxene, aegirine occurs in veins near skarn-like assemblages in a zone where dioritic sheets were emplaced into syenite. Other vein minerals are biotite, albite, K-feldspar, calcite, and ilmenite. The aegirine is almost pure NaFeSi₂O₆. Laser-ablation ICP-MS analysis shows that the aegirine crystals are typically lower in trace element concentrations than the calcic clinopyroxene of the complex. Chondrite-normalized rare earth element (REE) patterns show a prominent cup shape, and light REE abundances range from ∼0.1x to >10x chondrites.