OXIDI-S 



375 



precursors of the American Indian, must luivc used thi> natural 

 ma.miet tn orient their temples, as they are all placed parallel to the 

 magnetic meridian. Magnetite may be formed artificially by the 

 tii-ion of an iron silicate with lime. A large number of basic rocks 

 tu>ed in this \vay will yield magnetite. The black scales formed 

 on red-hot iron when cooling are magnetite. 



FRANKLINITE 



Franklinite. (Fe . Mn . Zn) (Fe . Mn) 2 O 4 ; Isometric ; Type, 

 Ditesseral Central; Common forms, o (111), d (110), other forms 

 rare; Cleavage, octahedral parting; Brittle, fracture conchoidal 

 to uneven ; H. = 5.5-6.5 ; G. = 5.07-5.22 ; Color, iron-black to 

 brownish black ; Streak, brown to black ; Luster, metallic ; 

 Opaque. 



I'ui. 437. Crystals of Franklinite in Calcitc. Franklin, New Jersey. 



B.B. Infusible ; fused with soda in the O. F. shows green so- 

 dium manganate. Fused with borax and soda in the R. F. on coal 

 yields a zinc coat. Slowly soluble in hot HC1. Some specimens 

 are quite magnetic. 



General description. Octahedral in habit with the edges 

 rounded as if fused, or truncated with the rhombic dodecahedron ; 



