Barwoodite
Barwoodite is an IMA-recognized mineral species in the silicate class, with the chemical formula Mn²⁺₆(Nb⁵⁺, )₂(SiO₄)₂(O,OH)₆.
It crystallizes in the hexagonal crystal system (space group P3). It is a member of the Welinite structural group.
Key properties: Mohs hardness 3.5; specific gravity 4.168; Light orange streak; Vitreous. Loses color very slowly in dilute HCl luster; optically uniaxial.
IMA symbol Bwo, IMA status: approved, named in 2017.
Found in miarolitic cavities in pegmatite in a nepheline syenite pluton.
It is found associated with Aegirine, albite, analcime, chamosite-pennantite, eggletonite, kupletskite, muscovite, natrolite, orthoclase, quartz, zircon.
The mineral was named to honor Dr. Henry (“Bumpi”) L. Barwood (1947-2016), an American clay mineralogist and surface chemist, Professor of Earth Science at Troy University (Troy, Alabama, USA).