| 词条 | Schiavinatoite |
| 释义 |
| name = Schiavinatoite | category = Borate, Oxide | boxwidth = | boxbgcolor = | image = Schiavinatoite-260476.jpg | imagesize = | caption = Schiavinatoite | formula = (Nb,Ta)BO4 | molweight = | strunz = 6.AC.15 | dana = | system = Tetragonal | class = Ditetragonal dipyramidal (4/mmm) H-M symbol: (4/m 2/m 2/m) | symmetry = I41/amd | unit cell = a = 6.22, c = 5.49 [Å] (approximated); Z = 4 | color = Colorless | habit = zones of prismatic dipyramidal crystals (intergrown with béhierite) | twinning = | cleavage = | fracture = | tenacity = | mohs = 8 | luster = Vitreous | polish = | refractive = n=2.30 | opticalprop = Uniaxial (+) | birefringence = Yes | 2V = | dispersion = | pleochroism = | fluorescence= | absorption = | streak = White | gravity = | density = 6.55 | melt = | fusibility = | diagnostic = | solubility = | diaphaneity = | other = | references =[1][2][3] }}Schiavinatoite is a very rare mineral,[2] a natural niobium borate of the formula (Nb,Ta)BO4.[3] Schiavinatoite is classified as monoborate. It contains tetrahedral borate anion instead of planar BO3 group, which is more common among minerals. Schiavinatoite is one of the most simple niobium minerals. It forms a solid solution with its tantalum-analogue, béhierite. Both minerals possess zircon-type structure (tetragonal, space group I41/amd) and occur in pegmatites.[2] Schiavinatoite and nioboholtite are minerals with essential niobium and boron.[4] Occurrence and associationSchiavinatoite was detected in miaroles of a pegmatite at Antsongombato, Madagascar. It coexists with an apatite-group mineral, béhierite, danburite, elbaite–liddicoatite, feldspar, pollucite, quartz, rhodizite, and spodumene.[1] Crystal structureThe main facts about schiavinatoite's structure:[3]
References1. ^1 {{cite web |url=http://www.handbookofmineralogy.org/pdfs/schiavinatoite.pdf |title=Schiavinatoite - Handbook of Mineralogy |website=Handbookofmineralogy.org |accessdate=2016-03-12}} {{mineral-stub}}2. ^1 2 {{cite web|url=http://www.mindat.org/min-7110.html |title=Schiavinatoite: Schiavinatoite mineral information and data |website=Mindat.org |accessdate=2016-03-02}} 3. ^1 2 Demartin, F., Diella, V., Gramaccioli, C.M., and Pezzotta, F., 2001. Schiavinatoite, (Nb,Ta)BO4, the Nb analogue of behierite. European Journal of Mineralogy 13, 159-165 4. ^{{cite web|url=http://www.mindat.org/min-43588.html |title=Nioboholtite: Nioboholtite mineral information and data |website=Mindat.org |accessdate=2016-03-03}} 4 : Borate minerals|Niobium minerals|Oxide minerals|Tetragonal minerals |
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