Rhodizite - Encyclopedia

    Class : Carbonates, Nitrates, Borates
    Subclass : Borates
    Crystal System : Cubic
    Chemistry : (K, Cs)Al4Be4(B, Be)12O28
    Rarity : Rare

Rhodizite is a rare borate in sodium pegmatites, where it occurs alongside elbaite, spodumene, apatite and lepidolite. Its relatively loose crystalline structure provides large cavities in which large ions can be housed : cesium, but also rubidium, lithium, potassium or sodium. Rhodizite is practically the only cesium mineral. Its name comes from the Greek rhodizein (to be pink), because when heated with a blowtorch the flame turns pink-red. Its crystals are yellow, greyish or white, frequently dodecahedral, sometimes tetrahedral and rarely exceed one centimeter. Rhodizite is translucent to transparent, vitreous to adamantine luster. It has a very limited use as a gem.

Main photo : Rhodizite from Ifasina, Sahatsiho Ambohimanjaka, Ambositra, Amoron'i Mania, Madagascar

Rhodizite from Ampasogona, Betafo, Madagascar © Jason B. Smith
Rhodizite from Tetezantsio, Betafo, Madagascar © Chinellato Matteo
Rhodizite from Tetezantsio, Betafo, Madagascar © Jordi Fabre
Rhodizite from Tetezantsio, Betafo, Madagascar © Lopatkin Oleg

Rhodizite in the World

All the most beautiful crystals come from the sodolithic pegmatites of Madagascar (Antsomgombato, Antandrokomby, Ambatofinandrahana), a 6 cm crystal is also kept at the Museum of the Ecole des Mines in Paris. It is also found in the Russian Urals (Mursinka, Sarapulca, near Neyvo-Schaytanskiy), where small millimetric crystals are sometimes implanted on rubellite crystals.

Rhodizite in France

Rhodizite is not present in the French underground.

Twinning and special crystallizations

A very rare twin is known on {111}.

Fakes and treatments

No fake identify for this mineral species.

Hardness : 8
Density : 3.30 to 3.38
Fracture : Conchoidal
Trace : White

TP : Translucent to transparent
RI : 1.689 to 1.691
Birefringence : 0
Optical character : None
Pleochroism : None
Fluorescence : Yellow-green

Solubility : Insoluble

Magnetism : None
Radioactivity : None