418 



Scientific Intelligence.— ^Mineralogy . 



euxenito from eu^svog, on account of the many rare substances it con- 

 tains. It is most nearly allied to the yttro-tantalite, yet it is distin- 

 guished from it by its specific gravity, its proportion of water, and 

 by its containing titanic acid, cerium, and lanthan. 



15. Native Gold in Suthcrhindsldrc. — A rounded piece of native 

 gold, weighing rather more than half an ounce, v*^as found some years 

 ago in the bed of the burn of Kildonan, a rapid mountain stream in 

 Sutherland. — Statistical Report of Kildonan, 



16. Tschewkinite, a new Mineral Species. — Description. Colour 

 velvet-black; in thin splinters, translucent and brown ; streak black- 

 ish-brown; lustre splendent and vitreous; nearly opaque; rather 

 harder than apatite; sp. gr. — 4.508 — 4.549. Occurs in the 

 Ilmengebirge near Miask, probably as a constituent of the miascite 

 which occurs there. Chemical Composition. — It appears from expe- 

 riments of Gustav Rose, to be principally a compound of silica, oxide 

 of cerium, oxide of lanthan, and oxide of iron. Externally, it much 

 resembles gadolinite, orthite, allanite, and thorite. All of them have 

 a black colour, conchoidal fracture, shining lustre, and gelatinise 

 with muriatic acid. We have, therefore, in the following table, 

 placed together the characters by which they are distinguished from 

 one another. 



I Gadoiimite. I 

 I (from Ytterby.) ! 



Orthite. 



Allanite. 

 (Greenland.) 



Thorite. I Ttsewkinite. 



Hardness, 

 Specific 

 Gravity, 



Relation to 

 Light, . . ' 



Colour of 

 the Powder. 



6.5 



4.238 



Pretty strongly 

 translucent on 



6.5 



3.1 



Feebly trans- 

 lucent on the 



. the edges, and edges, and tlun 

 I then it appears j it appears grcy- 

 , leek-green. ish green. 



j 1 



Mountain green.! Greyish-green. 



Relations 



before 



Blovvpiije. 



•ns ] 

 the > 

 pe, j 



Incandesces, 

 becomes grey- 

 ish-yellow, and 



is not fused. 



Swells and 



melts with 



frothing into a 



black glass. 



I 6 



I 4.173 



' Feebly trans- 

 lucent on edges, 

 and then it ap- 

 pears brown- 

 ish-green. 



Dark greyish- 

 I green. 



I Swells violently 

 I and is easily 

 1 melted into a 

 black globule, 

 which is attract- 

 iCd by the magnet. 



4.63 



Very feebly 

 translucent on 

 the edges, and 

 then it appears 

 brown. 



5.3 



4.549 



Very feebly 

 translucent on 

 the edges, and 

 then it appears 

 brown. 



Reddish-brown. Blackisli-brown . 



Becomes brown 



ish-red, but is 



not melted. 



Incandesces, 



swellsviokntly, 



becomes brown, 



and is melted 



into a black 



shining globule. 



17. Uranotantalite, a new Mineral Species. — Description. Colour 

 velvet-black ; streak dark reddish-brown ; occurs in imbedded flat 

 grains, sometimes the size of a hazel-nut; lustre splendent and im- 

 perfect metallic ; opaque; hardness between that of apatite and felspar ; 

 specific gravity = 5.025. Chemical composition. — From the expe- 

 riments of Gustav Rose, it appears to be chiefly composed of tanta- 

 lum and uranium, and is probably a tantalite of uranium ; hence 

 Rose names it uranotantal, according to the analogy o^ yttrotantal. 



18. Perowskitc, a new Mineral Species. — DescHption. Colour 

 greyish-black and iron-black ; streak greyish-white ; crystallized in 

 hexaJiedrons ; cleavage parallel with the faces of the crystals, and 



