Tetragonal; habit octahedral. G = 3·82-3·95. H = 5¹⁄₂-6. Transparent to opaque; brown to black. Dauphiné; Bavaria; Cornwall; Norway; Brazil, etc. _Ancylite._ 4Ce(OH)CO₃ + 3SrCO₃ + 3H₂O; with Fe, Mn, Ca, F, traces. Cer = 46·3%. Rhombic; prismatic. G = 3·95. H = 4¹⁄₂. Brown; translucent. Plain of Narsarsuk, Greenland. _Annerödite._ A parallel growth of Columbite on Samarskite, once believed to be a new species. Corresponding to Columbite. Arfvedsonite. Metasilicate of Na, Ca, Fe´´, Zr; approximately 4Na₂O,3CaO,14FeO,(Al,Fe)₂O₃,21SiO₂. ZrO₂ = 1-6%. Monoclinic--an amphibole. G = 3·44. H = 6. Black; pleochroism strong. S. Greenland and S. Norway. Arizonite. Ferric metatitanate, Fe₂O₃,3TiO₂ or Fe₂(TiO₃)₃. TiO₂ = 36·7%. Uncertain; apparently monoclinic. G = 4·25. H = 6-7. Dark steel-grey; opaque. Hackberry, Arizona. _Arrhenite._ Silico-tantalate of Yttrium metals, with Ce, Al, Fe, Ca, Be, aq. Yttr = 33·2; Cer = 2·6; ZrO₂ = 3·4%. Amorphous. G = 3·68. Red; translucent to opaque. Ytterby, Sweden. Astrophyllite. Titano-silicate of Fe, Al, Mn, Zr, K, Na, with aq. ZrO₂ = 1·2-4·5; TiO₂ = 7-14%. Rhombic. Cleavage (010) perfect. G = 3·2-3·4. H = 3. Golden to bronze yellow; strongly pleochroic. Brevik, Norway; El Caso Co., Colorado; Greenland. _Auerbachite._ An impure hydrated form of Zircon, ZrSiO₄. ZrO₂ = 55·2%. Tetragonal; isotropic. Pseudomorphous after zircon. G = 4·06. H = 6. Brownish-grey; translucent to opaque. Alexandrovsk, Russia. _Auerlite._ 3ThO₂,[3SiO₂,P₂O₅]6H₂O; traces of Fe, Ca, Mg, Al, CO₂, etc. SiO₂ replaced by P₂O₅/3? ThO₂ = 69·2-72·2%. Tetragonal; probably a pseudomorph after Thorite. G = 4·4-4·8. H = 2-3. Yellowish to orange-red. Henderson Co., N. Carolina. ~Baddeleyite.~ ZrO₂, with small amounts of SiO₂, Fe₂O₃, Al₂O₃, CaO, etc. ZrO₂ = 96·5%. Monoclinic. G = 4·4-6·0. H = 6¹⁄₂. Brown; pleochroic. São Paulo, Brazil; Rakwana, Ceylon. _Bagrationite._ A variety of Allanite (orthite) with no important chemical difference. Monoclinic; habit prismatic. G = 3·84. H = 6¹⁄₂. Black; translucent to opaque. Achmatovsk, Urals. _Bastnäsite_ (Harmatite). Hydrated fluocarbonate of Cerium metals, E(F)CO₃. Cer = 64-93·5; ThO₂ = 0-10%. Hexagonal prisms, pseudomorphous after Tysonite (_q.v._); or massive. G = 4·9-5·2. H = 4-4¹⁄₂. Yellow to brown; transparent. Bastnäs, Sweden; Pike’s Peak, Colorado. ~Beckelite.~ Zirconosilicate of rare earths and lime, Ca₃E₄(Si,Zr)₃O₁₅. Cer = 59·7; Yttr = 2·8; ZrO₂ = 2·5%. Cubic, in octahedra and dodecahedra. Cubic cleavage. G = 4·15. Brown; transparent. Near Sea of Azov, Russia. Benitoite. A Titano-silicate of barium, BaTiSi₃O₉. TiO₂ = 20·1%. Rhombohedral. H = 6¹⁄₂-7. Colourless to blue; transparent; pleochroism strong. Source of San Benito River, California. ~Blomstrandine.~