Narsarsukite: Gemstone Information
Narsarsukite is cited in Fleischer’s Glossary of Mineral Species (2004) as Na2(Ti,Fe3)Si4(O,F)11 and is described by Gaines et al. in Dana’s New Mineralogy [System of Mineralogy 8th edition] 1997 as Na2(Ti,Fe,Zr) [Si4O10](OH,F). Olive-green tetragonal crystals of small size with a hardness of 6–7 and SG 2.78 show a perfect cleavage in one direction.The RI for the ordinary and extraordinary rays is 1.610–1.614 and 1.644–1.647, uniaxial positive with birefringence 0.033. Narsarsukite occurs at Mt Saint Hilaire, Quebec, Canada.