Narsarsukite Locality: Poudrette quarry (Demix quarry; Uni-Mix quarry; Desourdy quarry), Mont Saint-Hilaire , Rouville RCM, Montérégie , Québec , Canada ( Locality at mindat.org ) A SUPERB example of the rare YELLOW Narsarsukite to my knowledge found only here. In any case, its certainly gotta be the prettiest possible examples for the species and as for that, this thumbnail is one of the best I have seen (not the biggest mind you, but aesthetically as a specimen, its up there!). It features a perfectly balanced 1.3 cm crystal perched nicely on matrix and comes from the noted Marcelle and Charles Weber Collection. It is somewhat more translucent in person than it appears here. 2.6 x 2.0 x 1.4 cm — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Narsarsukite
A rare sodium-titanium-iron silicate described in 1900 from Greenland's Narsarsuk pegmatite in the Ilímaussaq complex.
Intro adapted from Wikipedia (CC BY-SA).
Narsarsukite is an IMA-recognized mineral species in the silicate class, with the chemical formula Na₂(Ti,Fe³⁺)Si₄(O,F)₁₁.
It crystallizes in the tetragonal crystal system (space group I4/m).
Key properties: Mohs hardness 5.5–7; specific gravity 2.64–2.83; White streak; Vitreous, pearly on {110} luster; refractive index 1.62; optically uniaxial.
IMA symbol Nar, IMA status: approved, named in 1901.
Found in pegmatite (Narss^a rssuk, Greenland); in quartz veins in syenite intruding limestone (Sweetgrass Hills, Montana, USA); in hornfels, igneous breccia.
It is found associated with Aegirine, microcline, albite, elpidite, epididymite, taeniolite, quartz (Narss^arssuk, Greenland); aegirine, pectolite, calcite, feldspar, galena.
The name refers to the Greenland locality at Narss^a rssuk (Narsarsuk).