Apophyllite-(NaF)
NaCa4Si8O20F • 8H2O [CNMNC approved formula]
Named from the Greek apophylliso - "it flakes off" and the composition containing Na.
| IMA status : | Renamed IMA Approved; 2008 (IMA1976-032) |
| CLASSIFICATION | |
| Dana (8th edition) : |
72.03.01.03 |
| (72) Phyllosilicate Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings | |
| (72.03) with 3-, 4-, or 5-membered rings and 8-membered rings | |
| (72.03.01) Apophyllite group (4- & 8-membered rings) | |
| Nickel-Strunz (10th edition) : |
09.EA.15 |
| (09) Silicates | |
| (09.E) Phyllosilicates | |
| (09.EA) Single nets of tetrahedra with 4-, 5-, (6-), and 8-membered rings | |
| Crystal system: | Orthorhombic System |
| Point group (H-M): | mmm (or 2/m 2/m 2/m) — dipyramidal |
| Unit cell: | a = 8.87Å, b = 8.88Å, c = 15.79Å |
| Crystal Habit: | Crystalline; Massive ; Pseudo Cubic |
| Color: | White, Pink, Green, Yellow, Violet. |
| Diaphaneity: | Transparent to Translucent |
| Luster: | Vitreous |
| Hardness (Mohs): | 4 - 5 |
| Measured Density: | 2.3 - 2.4 g/cm3 |
| Cleavage: | {001} Perfect |
| Synonyms/varieties: | Natroapophyllite |
| Comments: | IMA approved 1976 as Natroapophyllite. Renamed to Apophyllite-(NaF) in 2008. |
Pale pink opaque blocky crystal Apophyllite-(NaF) aggregate.Origin: Boghil Quarry, Glengormley, Newtownabbey, County Antrim, Northern Ireland.
Photo: Jeff Weissman