/berr"treuhn duyt'/ , n.
a mineral, hydrous beryllium silicate, Be 4 Si 2 O 7 (OH) 2 , colorless or pale yellow, with a vitreous luster, occurring as tabular or prismatic crystals in pegmatites and hydrothermal veins.
[ 1885-90; Bertrand, French mineralogist, who first described it; see -ITE 1 ]