| Narsarsukite | |
| Category: | Silicate mineral |
| Imasymbol: | Nar[1] |
| Strunz: | 9.DJ.05 |
| System: | Tetragonal |
| Class: | Dipyramidal (4/m) H-M symbol: (4/m) |
| Symmetry: | I4/m |
| Unit Cell: | a = 10.72, c = 7.95 [Å]; Z = 4 |
| Color: | Honey to lemon-yellow, reddish brown, brownish gray, tan, pink; may be green from inclusions; may show color zoning |
| Habit: | Occurs as flat tabular to equant, striated crystals In divergent, radiating groups; massive |
| Cleavage: | Good on and |
| Fracture: | Uneven to subconchoidal |
| Tenacity: | Brittle |
| Mohs: | 5.5 - 7 |
| Luster: | Vitreous, pearly on |
| Streak: | White |
| Diaphaneity: | Transparent to translucent |
| Gravity: | 2.64-2.83 |
| Opticalprop: | Uniaxial (+) |
| Refractive: | nω = 1.609 nε = 1.630 |
| Birefringence: | δ = 0.021 |
| Pleochroism: | Weak; O = colorless to yellow; E = colorless to honey-yellow |
| References: | [2] [3] [4] |
Narsarsukite is a rare silicate mineral with either the chemical formula [2] or .[3]
It was first described in 1900 for an occurrence in the Narsarsuk pegmatite in the Ilimaussaq intrusive complex of West Greenland.[3] 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.[2] It occurs associated with aegirine, microcline, albite, elpidite, epididymite, taeniolite, pectolite, calcite, galena and quartz.[2]