Pyrochlore Supergroup (var: Betafite) with rare Fluorapatite association

Item Description

Here we have a fine quality, good sized and classic example of what used to be called "Betafite". For a long time Betafite was a valid species, named in 1912 after the Betafo District in Madagascar where the crystals were first discovered. It is now defined as a variety of the Pyrochlore Supergroup. The entry on mindat.org reads as follows, "True "Betafite" samples are structurally members of the pyrochlore supergroup. Hogarth (1977) stated that the betafite group has 2Ti ≥ (Nb + Ta), however the formulae of most betafites do not exactly correspond to pyrochlores and that difference has delayed their classification. The result of modern microprobe analyses is that almost all specimens formerly labeled betafite are no longer members of that group. New analyses, including determination of H^2O, OH, and F are necessary to identify the species of a particular sample. The root-name, betafite, was retained for historical reasons." With that said, you will likely still see these crystals labeled as Betafite. This piece is a wonderful example of this old classic material featuring a good sized, sharp, well-defined cuboctahedral crystal with a deep brown hue. What makes this specimen special is that it is intergrown with a dark reddish colored hexagonal prism of Fluorapatite, which is notably rare in my experience. The piece is in great condition on the top / display side, but it's not complete on the bottom Beautiful old classic material, and to find a piece with such smooth and well-formed faces is not terribly common. I'm told that these specimens were mined in the 1950s, and are certainly regarded as some of the finest examples of "Betafite" ever found.