ORES OF TELLURIUM. 219 



pounds. Tungstic acid is a fine yellow, even brighter than 

 chrome yellow ; but it turns green on exposure to the sun's 

 rays. 



The metal tungsten was so called from the Swedish word 

 tung, meaning heavy, the calcareous tungsten being pecu- 

 liarly heavy for an earthy looking mineral. It has also been 

 called scheelium, in honor of the chemist Scheele. 



Tungstate of lime. In square octahedrons ; A : A==100 1 

 8' and 130° 20'. Cleavage octahedral, perfect. Color yel 

 lowish-white, or brownish. Brittle. H=4 — 4-5. Gr= 

 6*075. Composition, tungstic acid 7*8, lime 19*06. Infu 

 sible alone, or only on the thinnest edges. Found with wol 

 fram at Lane's mine, Munroe, Conn. 



8. VANADIUM. 



Vanadium is a rare metal. It is found in nature as vanadic 

 acid in the vanadate of lead (p. 285), and vanadate of cop- 

 per (p. 302), and also combined with lime. The last men- 

 tioned has a brick-red color, a foliated structure, and a bright 

 shining luster. 



9. TELLURIUM. 



Tellurium occurs native, and also in combination with 

 gold, silver, lead, and bismuth. 



The metal is distinguished from arsenic and selenium 

 by giving no odor before the blowpipe ; from antimony 

 and bismuth by affording fumes in a glass tube below 

 the temperature of fusing the glass ; and when heated on 

 charcoal, the oxyd covers the coal with a brownish -yellow 

 oxyd, like bismuth ; but the inner flame directed on this oxyd 

 is tinged bright green, while bismuth gives no color. This 

 last test distinguishes also the ores of tellurium. 



Native tellurium occurs in six-sided prisms, of a tin-white color, and 

 al o massive. Brittle. H — 2 — 25. Gr — 6-1 — 6-3. Compusiti n, 

 pure tellurium with a little gold. From Transylvania. 



Telluric Ochre. Occurs with native tellurium in Transylvania i 

 small whitish or yellowish masses, radiated in sir cture, and also as i:i 

 earthy coaling. Supposed to he tellurous acid. 



In wlia* minerals is vanadium found? How does tellurium ore: 

 nature? How is this metal distinguished from arsenic and seiemun- 



