Tags: Chemical Substance, Mineral.
Beryllonite is a rare sodium beryllium phosphate mineral with formula NaBePO4. The tabular to prismatic monoclinic crystals vary from colorless to white or pale yellowish and are transparent with a vitreous lustre. Twinning is common and occurs in several forms. It exhibits perfect cleavage in one direction. The hardness is 5.5 to 6 and the specific gravity is 2.8. Refractive indices are nα = 1.552 nβ = 1.558 and nγ = 1.561.
