Londonite on Feldspar

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This is just a stunning (and important) londonite matrix piece from Madagascar from the type locality, out of the Paul Stahl collection. Londonite is a complex borate that is the rare cesium-rich analog of rhodizite. This well-balanced small cabinet piece is composed of a single, although possibly compound, well-formed, bright yellow, very lustrous, 3.1 cm, translucent to slightly transparent londonite crystal that is prominently displayed on a white orthoclase matrix accompanied by minor intergrown, gray quartz. The londonite is dominated by a single crystal that looks like it has at least one other, tightly intergrown, parallel growth crystal that is barely discernible. The large, handsome crystal is in excellent condition on the display side and actually complete all around, with a contact on the back. Nicely composed and displays well on its own. Ex. Paul Stahl collection; and he obtained it from Dr. Federico Pezzotta, who brought the best of them out in the early 2000s. This would have been found circa 2000-2002, when the big ones came out...nothing of this caliber has been found since. At the time, these were labelled as rhodizite and sold as rhodizite, before being recognized as a new species and named after our friend Dr. Dave London. If you look on Mindat at the moment, you will see this note: specimens from Madagascar without analysis should be labelled as londonite-rhodizite series. Many crystals contain complex patchy zones of both londonite and rhodizite which are only visible by back-scattered electron imaging (Simmons et al. 2001). While this is true, and one should RAMAN-analyze specimens individually, usually these darker yellow crystals have turned out to be primarily, vastly, londonite ons pot analysis of the surface. There would be some rhodizite zoning, within the crystal - but the surface, when this style and size and color, has in our experience proven to be nearly totally the londonite end-member of this chemical series of species. Because of the balance, color, size, and display quality, we consider this one of the more important examples (which is why Paul, known for his amazing taste in rare species, kept it for several decades!).