Yegorovite

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

Yegorovite is colorless, with a white streak. Found in small quantities among pegmatites. It is a natural silicate of alkali cations.^[1][2]

Chemical composition

The 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

The 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).

References

1. Pekov, I. V. et al., 2010, Yegorovite, Na4[Si4O8(OH)4]·7H2O, a New Mineral from the Lovozero Alkaline Pluton, Kola Peninsula. Geology of Ore Deposits 52.7 (2010): 584–590.
2. https://www.mindat.org/min-38851.html