250 PHYSIOGRAPHY. 



Tungsten Tungstic Ochre. 



Brittle. Hardness =4-0 . . . 4-5. Sp. gr. = 6-076, a 

 white cleavable variety from Schlaggenwald. 



Compound Varieties. Twin-crystals. Axis of revolu- 

 tion perpendicular, face of composition parallel to faces 

 truncating the base of the octahedron, a. The individuals 

 are continued beyond the face of composition. Reniform 

 shapes; surface drusy, composition columnar. Massive: 

 composition granular, faces of composition sometimes irreg- 

 ularly streaked. 



1. Heated upon charcoal, it decrepitates at first, and then fuses, but 

 only with great difficulty and on the thinnest edges into a semi-transpa- 

 rent, vitrified mass. It gives a white glass with borax, the transparen- 

 cy of which is proportioned to the quantity of the salt employed. 



2. Analysis. 



By BERZELIUS. 



Lime . . . . . . . 19-40 



Tungstic acid 80-42 



3. Tungsten occurs mostly in the repositories of Tin-Ore, and is ac- 

 companied by Wolfram, Topaz, Fluor and Quartz. It is also found ia 

 lead veins with Wolfram and Spathic Iron. 



4. Its most remarkable localities are Schlackenwald and Zinnwald in 

 Bohemia, Zinnwald and Ehrenfriedersdorf in Saxony, and Cornwall, 

 England. It is also found in Sweden and Dauphiny. It occurs in large 

 irregular crystals and massive at Monroe, in Quartz with Wolfram, Ga- 

 lena, Native Bismuth and Tungstic-ochre ; also in the adjoining town of 

 Trumbull in a vein of Topaz, Quartz and Fluor. 



TUNGSTIC OCHRE. Tungstic Lusine-Ore. 



Massive : composition impalpable ; earthy and pulveru- 

 lent. Fracture earthy. 



Color lemrnon-yellow. 



Soft. Sp. gr. =6-0. 



1. It assumes a greenish hue when strongly heated. It combines 

 with the acids and is soluble in caustic alkalies. 



2. It is probably tungstic acid in a state of perfect purity, and there- 

 fore consists of Oxygen 13-55. and Tungsten 86-45, 



