TANTALUM. 1. Oblique four-sided prism, with lateral edges of 95« ~ and 85° ? 2. Six-sided prism, with two lateral edges of 95°, and four others of 132 s * 30'; or with two lateral edges of 95°, and two others of 144° 50', and two others of 120° 10'. Internally it is shining or glistening, and the lustre is resinous, sometimes inclining to metallic. It occurs in granular distinct concretions. It is opaque. It scratches glass, but does not afford sparks with .steel. It yields a grey-coloured powder. It is brittle. Specific gravity, 5.130, Ekeberg. Chemical Characters. On the first application of the flame of the blowpipe it decrepitates ; but if the heat is increased, it melts into $ greenish-yellow slag. Constituent Parts. Oxide of Tantalum, - 45 Oxide of Iron and Yttria, 55 100 Vauquelin, Hauy, Tabl. p. 309. Geognostic and Geographic Situations. It occurs along with gadolinite, in a bed of flesh-red felspar, in gneiss at Ytterby near Itoslagen in Sweden. Observations.