is a Sodium Titanium Iron Silicate Fluoride with formula Na2(Ti, Fe)Si4(O, F)11 and hardness of 6-7. It is named for the famous mineral location Narsarsuk in Greenland where it was discovered over 100 years ago. This piece here comes from Mount Saint -Hilaire,Quebec,Canada and is considered a very big size: I have read on the web that 0.31 ct. was the largest known nasarsukite cut gemstone.
Size: 10x7.3x4.2 mm.
Weight: 1.32 ct.