Yegorovite, ([Na4[Si4O8(OH)4]·7H2O]) is a silicate mineral found in a hyperalkaline pegmatite in the Lovozero Pluton at Mt. Kedykverpakhk in the Kola Peninsula of Russia. It was named in memory of Russian crystallographer Yurii Kavdievich Yegorov-Tismenko, and approved by the Commission on New Minerals and Mineral Names, International Mineralogical Association in 2008.[1]
| Yegorovite | |
|---|---|
| General | |
| Category | Silicate mineral |
| Formula (repeating unit) | Na4[Si4O8(OH)4]·7H2O |
| IMA symbol | Yeg |
| Strunz classification | 09.DX.00 |
| Dana classification | 65.01.09.01 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic H–M symbol: (2/m) |
| Space group | P22/c |
| Unit cell | a = 9.866(7) Å, b = 12.385(5) Å, c = 14.921(1) Å, β = 104.79(6)°, V = 1762(3)ų |
| Identification | |
| Color | colorless |
| Twinning | Polysynthetic |
| Cleavage | perfect on {(010) and (001)} |
| Fracture | splintery |
| Mohs scale hardness | 2 |
| Luster | Vitreous |
| Streak | white |
| Diaphaneity | Opaque |
| Specific gravity | 1.90 |
| Density | 1.90(2) g/cm³ |
| Optical properties | biaxial (−) |
| Birefringence | δ = 0.008 |
| References | [1][2] |
Physical properties
editYegorovite is colorless, with a white streak. Found in small quantities among pegmatites. It is a natural silicate of alkali cations.[1][2]
Chemical composition
editThe chemical composition of yegorovite in elemental weight percent is as follows:
| element | weight % |
|---|---|
| Na2O | 23.28 |
| SiO2 | 45.45 |
| H2O | 31.27 |
| Total | 100.0 |
Crystal structure
editThe crystal structure of yegorovite is made up of a single chain of four silicon (Si) tetrahedrons [Si4O8(OH)4]∞ and sixfold polyhedrons of [NaO(OH)2(H2O)3] and [NaO(OH)(H2O)4] centered by sodium (Na).