[60] Pogg. Ann. 1839, 48, 555.
[61] Ibid., 1847, 71, 157.
In 1907, Brögger[62] announced that Annerödite, of which he had published an account as a new species in 1881, was a parallel growth of the mineral columbite, (Fe,Mn)Cb₂O₆, on samarskite.
[62] Abstr. Chem. Soc., 1907, 92, ii. 885.
Both minerals are orthorhombic, but they are not isomorphous. The mistake was due to the fact that whilst the crystallographic data were determined from the upper crystals of columbite, the crystals of samarskite were used for analysis.
Plumboniobite.
[63]—This is a recently discovered mineral closely related to samarskite and [yttrotantalite] (q.v.). It is essentially a columbate[64] of yttrium metals, lead and uranium, with water, ferrous oxide, titanium dioxide, stannic oxide, alumina, lime, and cuprous oxide. The formula given is R´´₂Cb₂O₇,R´´´´₄(Cb₂O₇)₃, where R´´ = (Fe,Pb,Ca,UO), and R´´´ = Al and yttria metals, with isomorphous (?) metatitanate. The mineral is radio-active, and gives considerable quantities of gas on being heated with sulphuric acid (carbon dioxide 0·19, helium and nitrogen 0·22 per cent.). The yttria earths are rich in the oxides of gadolinium and samarium, and the mineral should prove a valuable source of these elements. It is remarkable that the ceria earths are almost entirely absent.
[63] Hauser u. Finch, Ber. 1909, 42, 2270; Hauser, ibid., 1910, 43, 417.
[64] It is to be understood that small quantities of columbium are replaced by tantalum.
The mineral is massive, with some indication of crystalline structure. It is dark brown to black, transparent in flakes, and under the microscope is seen to be isotropic, with doubly-refracting inclusions, undoubtedly of a secondary nature. Hardness 5 to 51⁄2; sp. gr. 4·80 to 4·81. Unlike samarskite, it does not glow on ignition.