GADOLINITE. 565 Observations. It is very nearly allied both to gadolinite and tantalite. It is distinguished from gadolinite by its concretions, higher specific gravity, and the effect produced on it by the action of the blowpipe ; and it is distinguished from tantalite by its granular concretions, specific gravity, and its imperfect fusibility. 3. Gadolinite. Gadolinit, Karslen. Gadolinit, Geyer, in V. Crell’s Chem. Annal. 1788, b. i. s. 229. —Gadolin, in K. Sv. Acad. n. Ilandl. 1794,11— 1 Gadolinite, Hauy, t. iii. p. 141. Id. Reuss, ii. 2. 7- id. Karsten, Tabel. s. 22. Id. llauy, Tabl. p. 47- Id Eaus. Handb. b. ii. s. 608. Id. Aikin, p. 128. / External Characters. Its colour is velvet-black, sometimes greenish-black, less frequently brownish-black, and very rarely hyacinth- red. It occurs massive, disseminated ; and rarely^ crystalli sed in oblique four sided prisms; sometimes also in six- sided prisms ; and it is said also in rhomboidal dodecahe drons. Internally it is shining, and the lustre is resinous, in clining to vitreous. The fracture is generally conchoidal; seldom uneven. It appears sometimes to occur in distinct concretions, which are granular or prismatic ; and the surfaces of the concretions have frequently a whitish or bluish aspect, »nd varv from glistening to dull. N n 3 It'