PHYSIOGRAPHY. 



Columbite Common Salt. 



141 



of this species which the United States have afforded, have been found 

 atAcworth, (New Hampshire,) but the locality appears to be exhausted. 



APPENDIX TO COLUMBITE. 

 Brown Tantalite of Kimito. BERZELIUS. 

 Sp. gr. = 79. Powder cinnamon-brown. 

 When heated with borax, in a very fine powder, it is with dif- 

 ficulty dissolved. The glass does not possess the color of the ox- 

 ides of iron, except a dark green color, which exists only during 

 the experiment. With salt of phosphorus, it is readily dissolved. 

 It becomes minutely divided with soda, but does not dissolve, giv- 

 ing in the reduction flame a little tin, and upon platina-foil the re- 

 action of manganese. 



2. Analysis. 

 By BERZELIUS. 

 Columbic acid . . . 82-56 



Protoxide of iron . . . 14-41 



Protoxide of manganese . . 1-79 



Oxide of tin ... 0-56 



Silica . . . 0-72 



It is probable that future researches may render it necessary to divide 

 the species Columbite, but at present our knowledge of the properties of 

 its varieties do not justify the procedure. 



COMMON SALT. Hexahedral Rock-Salt. 



MOHS. 



Primary form. Cube. 

 Secondary forms. 



Fig. 145. Fig. 146. 



3. Octahedron. 



Cleavage, parallel with the cube, perfect; rarely also 

 the crystals cleave parallel with the diagonals of this form. 



V 



