ABSTRACT: Niobium and tantalum are very similar elements, and they occur together in a number of rare minerals. One of the rarest tantalumbearing species is behierite, a borate of tantalum $\rmTaBO_4$, which has ben found so far only in Madagascar, and whose crystal structure type is that of zircon; recently, the niobium equivalent of behierite ($\rmNbBO_4$) has also been discovered in Madagascar and has been named schiavinatoite in honour of Giuseppe Schiavinato