Class : Phosphates, arsenates, vanadates
    Subclass : Anhydrous phosphates
    Crystal System : Monoclinic
    Chemistry : NaBePO₄
    Rarity : Rare

Beryllonite is a secondary phosphate of sodium and beryllium of granitic pegmatites. It accompanies other phosphates (hertherite, eosphorite, etc...), as well as beryl, quartz and commonly lepidolite, cassiterite, apatite and columbite. It owes its name to its chemical composition rich in beryllium. It forms crystals of various habitus, frequently tabular and with coarse faces, reaching up to 25 cm, as well as spherical aggregates with fibrous textures. The crystals are commonly twinned, forming pseudohexagonal star buildings. Beryllonite is colorless to white and pale yellow, sometimes greenish or brown. It is a mineral which is very occasionally cut as a gemstone.