46 



PHYSIOGRAPHY. 



Microlite. 



Secondary forms. 



Fig. 302. 



Fig. 303. 



Cleavage, parallel with the primary faces, imperfect. 

 Fracture conchoidal, passing to uneven. Surface of the 

 primary faces, generally dull; those of b also. 



Lustre resinous. Color straw-yellpw, to dark reddish- 

 brown. Transparent to translucent on the edges. Streak 

 white, except when the color of the mineral is brown ; 

 it then resembles the color. 



Brittle. Hardness = 5-0...5-5. Sp. gr. = 4-75 . . . 5-00. 



1. Alone before the blow-pipe, it remains unaltered. It is slowly dis- 

 solved in the glass of borax, to which it communicates a yellow color, that 

 grows paler on cooling, but remains transparent unless subjected to fla- 

 ming, when it becomes nebulous, and presents on cooling, a pale yellow 

 enamel. It is not readily acted upon by carbonate of soda. Insoluble 

 in nitric acid. Its chief ingredient is probably the oxide of cerium. 



2. It is found at Chesterfield, (Mass.) in the vein of Albite, which 

 contains the green and red Tourmaline. The largest crystals yet seen, 

 weigh but 0-4 of a grain. They are disseminated through the Albite, 

 particularly near its junction with the smoky Quartz, 



MIEMITE. (See Dolomite.') 

 MIKROKLIN. (See Feldspar.) 



MlMETENE. 



Primary form. Regular hexagonal prism. 

 Secondary form. Terminal edges replaced by single planes. 

 Cleavage, parallel with the primary faces, imperfect ; scarcely 

 visible parallel to the bases of the prism, 



