Summary: The complex kalsilite-bearing melilite-nephelinite from Mt. Shaheru in the Belgian Congo with götzenite, combeite, and kirschsteinite contains yet another new silicate for which the name delhayelite is proposed.

Delhayelite is orthorhombic with a 6·53, b 24·65, c 7·04 Å. Possible space-groups Pmn2₁ and Pmmn. Weak super-cell with doubled a-axis. Distinct cleavage parallel to (010). Birefringence weak. α ≈ β ≈ γ = 1·532. 2V_α = 83°. Optical orientation: a = α, b = γ, c = β. Sp. gr. 2·60. Chemical composition corresponds to the tentative formula (Na,K)₄Ca₅Al₆Si₃₂O₈₀.18H₂O.3(Na₂,K₂)(Cl₂,F₂,SO₄).