Yttrocrasite.
[55]—This is a complex titanate of rare earths (chiefly yttria earths) with lime, thoria, and oxides of lead, iron, uranium, etc.; it has a considerable water content. An approximate formula is R´´O,RivO₂,3R´´´₂O₃,16TiO₂,6H₂O, where R´´ = (Ca,Pb,Fe), Riv = (Th,U), and R´´´₂O₃ = rare earths. No constitutional formula can be given; it will be noticed that the amount of titanium dioxide is considerably more than is required to combine with the bases present (cf. also [Delorenzite] below). It is radioactive.
[55] Hidden and Warren, Amer. J. Sci. 1906, [iv.], 22, 515; also Zeitsch. Kryst. Min. 1907, 43, 18.
Imperfect crystals only were found, apparently belonging to the orthorhombic system. No crystallographic data could be determined.
The mineral is black, closely resembling [polycrase and euxenite] (q.v.) in appearance. Hardness 51⁄2-6; sp. gr. 4·80.
It is infusible, and not easily soluble in acids. Hydrofluoric acid decomposes it, and the powdered mineral is also slowly attacked by boiling concentrated sulphuric acid.
It was found in 1904 by Barringer, in Burnet Co., Texas.
Delorenzite.
[56]—A compound similar to the above, but even richer in titanium dioxide, which amounts to 66 per cent. Tin dioxide is also present, with traces of columbic anhydride. The bases are the yttria earths (almost free from ceria earths), uranium dioxide, and some ferrous oxide, the formula being 2FeO,UO₂,2Y₂O₃,24TiO₂, with a little SnO₂ replacing TiO₂. It is strongly radioactive. Its closest chemical neighbour is yttrocrasite, but in appearance and angles it closely resembles [polycrase] (q.v.). Its discoverer, Zambonini, therefore formulates it as a metatitanate with titanium acting also as a base—polycrase is a mixed metatitanate and metacolumbate—thus, 2FeTiO₃ + U(TiO₃)₂ + 2Y₂(TiO₃)₃ + 7(TiO)TiO₃.
[56] Zambonini, Zeitsch. Kryst. Min. 1908, 45, 76.