228 ^fETALS. 



13. URANIUM. 

 The uranium ores have a specific gravity not above 7, and 

 a hardness below 6. The ores are either of some shade of 

 light green or yellow, or they are dark brown or black and 

 dull, or submetallic without a metallic luster when powdered 

 They are not reduced wljen heated with carbonate of soda ; 

 and the brown or black species fuse with difficulty on the 

 edges or not at all. 



pitchblende. — Oxyd of Uranium. 



Massive and botryoidal. Color grayish, brownish, or vel 

 vet-black. Luster submetallic or dull. Streak powder 

 black. Opaque. H^5-5. Gr==6'47. 



Composition ; 79 to 87 per cent, of protoxyd of uranium 

 with silica, lead, iron, and some other impurities. Infusible 

 alone before the blowpipe, but forms a gray scoria with 

 borax. Dissolves slowly in nitric acid, when powdered. 



Obs. Occurs in veins with ores of lead and silver in 

 Saxony, Bohemia and Hungary ; also in the tin mines of 

 Cornwall, near Redruth. In the United States, at Middle 

 own and Haddam, Conn. 



Uranic ochre is a light yellow pulverulent mineral, be- 

 coming orange yellow when gently heated. It is believed 

 to be peroxyd of uranium, sometimes combined with car- 

 bonic acid. Accompanies pitchblende in Cornvvall and in 

 Bohemia. It occurs sparingly in a yellow powder with co- 

 lumbite and uranite at the feldspar quarry, near Middletown, 

 Conn. 



Uses. The oxyds of uranium are used in painting upon 

 porcelain, yielding a fine orange in the enameling fire, and 

 a black color in that in which the porcelain is baked. 



Coracite (Le Conte). An ore resembling pitchblende, and probably 

 that species. From the north shore of Lake Superior, in a vein 2 

 inches wide, near the junction of trap and syenite. 



Eliasite. A similar ore, containing 10^ per cent, of water. 



UKANITE. 



Dimetric. In short square prisms, thinly foliated parallel 



What is said of the ores of uranium 1 Describe pitchblende. What 

 13 its composition 1 What are the uses of the oxyds 1 



