Rhodizite: Gemstone Information
Rhodizite is (K,Cs)Al4Be4(B,Be)12O28 and is found as well-formed transparent to translucent colourless to white dodecahedra and tetrahedra of the cubic system with hardness 8–8.5 and SG 3.44. The RI is 1.694 but rhodizite frequently displays anomalous birefringence. Some specimens give a strong greenish or yellowish response to X-rays with some phosphorescence and a weaker yellowish response under SWUV. Rhodizite occurs as a late-stage accessory mineral in alkali-rich granite pegmatites.Good crystals from Antandrokomby near Mt Bity and other locations in Madagascar and from near Sarapulka and Shaitanka, Ural Mts, Russia.Some Russian material is reported to show a rose-red colour.