266 METALS, 



18. COBALT. 

 Cobalt lias not been found native. The ores of cobalt 

 having a metallic luster, vary in specific gravity from 6*2 to 

 7*2 ; and the color is nearly tin-white or pale steel-gray, in- 

 clining to copper-red. The ores without a metallic luster 

 have a clear red or reddish color, and specific gravity of 

 nearly 3. The ores are remarkable for giving a deep blue 

 color to glass of borax, even when the proportion of cobalt 

 is small. 



smaltine. — Tin-white Cobalt. 



Monometric. Occurs in octahedrons, cubes, and dodeca- 

 hedrons, more or less modified. (See figs. 1, 2, 3, page 25, 

 and 32, 37, page 36.) Cleavage octahedral, somewhat dis- 

 tinct. Also reticulated ; often massive. 



Color tin-white, sometimes inclining to steel-gray. Streak 

 grayish-black. Fracture granular and uneven. H=5'3 — 

 Gr = 6-4— 7-2. 



Composition : essentially cobalt and arsenic ; the cobalt 

 varies from 18 to 23*5 per cent, and the arsenic from 69 to 

 79 per cent. A variety contains 9 to 14 per cent, of cobalt 

 and is called radiated white cobalt; another variety con- 

 tains iron. See further, Chloanthile. 



Gives off arsenical fumes in a candle. Colors borax and 

 other fluxes blue, and affords a pink solution with nitric acid. 



Dif. The arsenical cobalts are at once distinguished 

 from mispickel or white iron pyrites, by the blue color they 

 give with borax ; and also by their crystals and specific 

 gravity. 



Obs. Usually in veins with ores of cobalt, silver, and 

 copper. Occurs in Saxony, especially at Schneeberg ; also 

 in Bohemia, Hessia, and Cornwall. 



In the United States it is found in gneiss with copper 

 nickel, at Chatham, Conn. 



Cobaltine. This is another arsenical ore of* cobalt, containing sul- 

 phur as well as arsenic. Color silver-white, inclining to red. Con- 

 tains 33 to 37 per cent, of cobalt. Forms of crystals, figures 42, 46, 

 page 37. From Sweden, Norway, Siberia, and Cornwall. The mos! 



What is said of the ores of cobalt ? Describe tin-white cobal* X 

 What is its composition ? its blowpipe characters '? How is it distiR« 

 (fuished from mnpicke) and white iron pyrites? 



