Formula: Na4K3(Fe,Mn,Ti)2Si8O20(OH)4 . 4H2O
Origin of name: Named after Prof. Vadim Viktorovich Ershov (1939-1989) of the Moscow Mining Institute.
Crystal system: Triclinic
Crystal class: 1
Twinning:
Unit cell: a = 10.244, b = 11.924, c = 5.276, α = 103.136°, β = 96.033°, γ = 91.033°
Colour: Olive green, brown and yellow tinges
Diaphaneity: Translucent
Luster: Vitreous
Habit: Disseminated elongate grains to 10 mm, parallel fibrous aggregates to 3 cm, anhedral grains
Hardness: 2 to 3
Specific gravity: 2.75
Cleavage: 2; {100} and {101} perfect
Tenacity: Sectile
Streak: White
Synonyms/varieties:
Comments: Slightly soluble in weak solutions of HCl, HNO3 and H2SO4
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