Sodalite Na₈(Al₆Si₆O₂₄)Cl₂

Unit cell

Lattice constants

a = 8.870 Å, b = 8.870 Å, c = 8.870 Å; α = 90°, β = 90°, γ = 90°

Cell volume

697.9 ų

Atoms in the cell

46 (Cl 2, Na 8, Si 6, Al 6, O 24)

Formula units Z

1

Calculated density

1.91 g cm⁻³

Shortest contact

1.582 Å

Coordination

Cl

CN 4 at 2.69 Å (4 Na)

Na

CN 4 at 2.39 Å (3 O + 1 Cl)

Si

CN 4 at 1.58 Å (4 O)

Al

CN 4 at 1.76 Å (4 O)

O

CN 2 at 1.58 Å (1 Si + 1 Al)

About the structure

• The sodalite cage (β-cage): a truncated octahedron of 24 corner-sharing (Si,Al)O₄ tetrahedra. Cages share faces to fill space.
• Na⁺ and Cl⁻ sit inside the cages; swap Cl⁻ for S₃⁻ radicals and the same framework is ultramarine (lapis lazuli).
• The same cage is a building block of zeolite A and faujasite, so sodalite is the simplest way into zeolite structures.
• Coordinates from the Crystallography Open Database, entry 1011185 (open data); hydrogen and water sites with partial occupancy below 0.5 are left out.

Atom positions (fractional, one cell)

Z, coordination numbers, distances, density and packing on this page are computed from these coordinates.