Narsarsukite

Narsarsukite is a rare silicate mineral with either the chemical formula Na2(Ti,Fe(3+))Si4(O,F)11 or Na4(Ti,Fe)4[Si8O20](O,OH,F)4.

It was first described in 1900 for an occurrence in the Narsarsuk pegmatite in the Ilimaussaq intrusive complex of West Greenland. It has also been reported from a syenite which intruded limestone in the Sweetgrass Hills, Montana, and within hornfels and marble xenoliths in the alkalic intrusive of Mont Saint-Hilaire, Quebec. It occurs associated with aegirine, microcline, albite, elpidite, epididymite, taeniolite, pectolite, calcite, galena and quartz.