Mogovidite
Mineral of the eudialyte group
From Wikipedia, the free encyclopedia
Mogovidite is a very rare mineral of the eudialyte group,[3] It is similar to feklichevite, differing from it in the presence of essential vacancies (at the M3 site) and carbonate group.[4] Another specific feature is the dominance of ferric iron – a feature shared with other eudialyte-group members, including feklichevite, fengchengite, golyshevite and ikranite. Similarly to golyshevite, it is calcium-dominant, however on three (not two) sites: M(1), N(3) and N(4).[3][4] It has a molecular mass of 3,066.24 gm.[6] Mogovidite's formula given as Na9(Ca,Na)6Ca6(Fe3+,Fe2+)2Zr3[]Si(Si9O27)2(Si3O9)2(CO3)(OH,H2O)4.[4] The formula given is based on the original one but extended to show the presence of cyclic silicate groups.
| Mogovidite | |
|---|---|
| General | |
| Category | Cyclosilicate |
| Formula | Na9(Ca,Na)6Ca6(Fe3+,Fe2+)2Zr3[]Si25O72(CO3)(OH,H2O)4 (original form) |
| IMA symbol | Mgo[1] |
| Strunz classification | 9.CO.10 |
| Dana classification | 64.1.6 |
| Crystal system | Trigonal |
| Crystal class | Hexagonal scalenohedral (3m) H-M symbol: (3 2/m) |
| Space group | R3m |
| Unit cell | a = 14.23, c = 29.98 [Å] (approximated); Z = 3 |
| Identification | |
| Color | Brown to reddish-brown |
| Crystal habit | grains and crystals |
| Cleavage | No |
| Tenacity | Brittle |
| Density | 2.91 (measured) |
| Optical properties | Uniaxial (−) |
| Refractive index | nω = 1.62, nε = 1.61 (approximated) |
| References | [2][3][4][5] |
Occurrence and association
As golyshevite, mogovidite was discovered in calcium-bearing peralkaline pegmatites of the Kovdor massif, Kola Peninsula, Russia. The mineral name is of geographical origin – mogovidite is named after Mt. Mogo-Vid located in the vicinity of type locality. Association of mogovidite: aegirine-augite, andradite, calcite, humite, nepheline, pectolite, scolecite, titanite, zircon.[4]
