Other rarities occurring in the pegmatites of this area include microlite, hambergite and
rhodizite (Antandrokomby is one of the world's richest sources of this mineral).
From Ambalahe, Manapa, near Betafo, come very lustrous, striated, short-prismatic liddicoatite crystals with trigonal terminations, mostly around 3 cm but exceptionally to 12 cm, loose or on pegmatitic matrix; these crystals are a very dark greenish brown to black but have rich red internal highlights, and on a few of their surfaces rest sharp, lustrous, snow-white dodecahedral crystals of londonite (the cesium analog of
rhodizite first described in 2001) to 3 mm.
To add yet further spice, the sprinkling of pale ivory-white sparkling crystals on one side of the "sibirite" spray appears to be the extremely rare
rhodizite, a characteristic associate of sibirite from Shaitansk, which is the co-type locality.
Lino explains that since this material has tested extremely high in rubidium, it may in fact be neither
rhodizite nor londonite but a new species.
At the booth I noticed Erica Pohl, the wonderful collector from Switzerland, looking at a very fine, unusual specimen of
rhodizite from Madagascar.
The elbaite crystals reach 3 cm individually, and occur in floater groups of toenail to miniature size; what is more, grayish white, translucent dodecahedrons of
rhodizite to 5 mm are sprinkled liberally on their surfaces, for a fetching white-on-black effect.
Another whole shelf was full of large yellow crystals of what used to be called
rhodizite, but is now recognized as the new mineral londonite (the cesium analog of
rhodizite) from Mahaica, Madagascar.
Relationship to other species: It is the Cs-dominant analogue of
rhodizite, (K,Cs)[Al.sub.4][Be.sub.4][(B,Be).sub.12][O.sub.28].
Londonite, a New Mineral: the Cs-dominant Analog of
Rhodizite from Madagascar
The Italians are heavily connected with mining in Madagascar and so numerous large and fine crystals of
rhodizite were available, especially from Lino Caserini, and liddicoatites (some on matrix) from Enio Prato.
And everyone should be informed that many of the very large, very yellow and lustrous, very attractive crystals from Madagascar that heretofore have been called "
rhodizite" have now been shown to be londonite, a new species which is the cesium analog of
rhodizite, i.e.
The Sarapulka and Shaitanka pegmatites are irregular thin veins containing rubellite and
rhodizite in the west and green and blue aquamarines in the east.