Rhodizite

General Information: Chemical Formula:(K,Cs)Al4Be4(B,Be)12O28 Composition:(Molecular Weight = 778.83 gm)Cesium 4.27 % CsPotassium 3.77 % K Beryllium 8.10 % BeAluminum 13.86 % AlBoron 12.49 % B Oxygen 57.52 % O  Empirical Formula: K0.75Cs0.25Al4Be412(B0.75)12(Be0.25)O28 IMA Status:Approved IMA 1965Physical Properties: Cleavage:[???] Indistinct Color:colorless, grayish, yellow, yellowish white, or white. Density:3.44 Diaphaniety:Transparent to Translucent Hardness:8.5 - Chrysoberyl Luster:Vitreous - Adamantine Streak:whiteMore details...

(K,Cs)Al4Be4(B,Be)12O28