Nabesite is a rare silicate mineral of the zeolite group with the chemical formula Na₂BeSi₄O₁₀·4(H₂O). It occurs as colorless to white orthorhombic crystals in thin platy mica like sheets. It has the zeolite structure. Its Mohs hardness is 5 to 6 and its specific gravity is 2.16. The reported refractive index values are nα=1.499, nβ=1.507, and nγ=1.511.