Arctite
Na5Ca7Ba(PO4)6F3 [CNMNC approved formula]
Named for the arctic region where it was found.
| IMA status : | Approved Species 1981 (IMA1980-049) |
| CLASSIFICATION | |
| Dana (8th edition) : |
41.05.18.01 |
| (41) Anhydrous Phosphates Containing Hydroxyl or Halogen | |
| (41.05) where (A B)2 (XO4) Zq | |
| (41.05.18) | |
| Nickel-Strunz (10th edition) : |
08.BN.10 |
| (08) Phosphates, Arsenates, Vanadates | |
| (08.B) Phosphates, etc. with Additional Anions, without H2O | |
| (08.BN) With only large cations, (OH, etc.):RO4 = 0.33:1 | |
| Crystal system: | Trigonal System |
| Point group (H-M): | 3m (or 3 2/m) — hexagonal-scalenohedral |
| Unit cell: | a = 7.094 Å, c = 41.320 Å |
| Color: | Colorless |
| Diaphaneity: | Transparent |
| Luster: | Vitreous, pearly on cleavages |
| Hardness (Mohs): | 5 |
| Measured Density: | 3.13 g/cm3 |
| Cleavage: | 1; {0001} perfect |
| Streak: | White |
| Geologic Setting: | A late-stage pneumatolytic mineral in pegmatitic veinlets in a differentiated alkalic massif. |
| Mineral Association: | Natrosilite, vuonnemite, lomonosovite, zirsinalite, natisite, rasvumite, villiaumite, aegirine, thenardite, umbite, paraumbite, kostylevite, wadeite |
Origin: Koashva Mt, Chibiny, Kola, RussiaSample size: 2.5 x 4 cm
Photo: Diederik Visser
(zoom-in of above)