Schiavinatoite Locality: Antsongombato gem mine, FKT Antsentsindrano, Andrembesoa Commune, Betafo District, Vakinankaratra Region , Antananarivo Province , Madagascar ( Locality at mindat.org ) Size: 5.6 x 3.9 x 3.5 cm. This is a newly named (1999), extremely rare mineral from Madagascar. Embedded in quartz are sub-metallic, taupe-gray crystals to 2 cm in length. I obtained this in exchange from Dr. Pezzotta, who specializes in the minerals of Madagascar and I think could be safely considered the authority on finely crystallized rarities here. He told me these are among the largest fine crystals known for the species. I certainly have seen nothing comparable on the market, and for that matter you don't see much of it at all on the market. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Schiavinatoite
The niobium end-member of the béhierite series — a rare tetrahedral-borate mineral.
Intro adapted from Wikipedia (CC BY-SA).
Schiavinatoite is an IMA-recognized mineral species in the borate class, with the chemical formula Nb(BO₄).
It crystallizes in the tetragonal crystal system (space group I4_1/amd). It is a member of the Zircon structural group.
Key properties: Mohs hardness 8; specific gravity 6.548; White streak; Vitreous luster; optically uniaxial.
IMA symbol Shv, IMA status: approved, named in 1999.
Very rare in miarolitic cavities in a pegmatite dike.
It is found associated with Béhierite, rhodizite, elbaite–liddicoatite, spodumene, pollucite, danburite, apatite, quartz, feldspar.
The mineral was named to honor Professor Guiseppe Schiavinato (1915–1996), Italian mineralogist, who supported the advancement of mineralogy in Italy.