400 PHYSIOGRAPHY. CLASS it. 



LEONH. S. 349. Fer oxydute. HAUY. Traite, T. IV. 

 p. 10. Tabl. comp. p. 93. Traite, 2de Ed. T. III. 

 p. 560. 



Fundamental form. Hexahedron. Vol. I. Fig. 1. 



* 



Simple forms. H, Gulsen, Stiria ; O (P), Vol. I., 



Fig. 2., Fahlun, Sweden ; D (/), Vol. I. Fig. 31., 

 Traversella, Piedmont; A 2, Vol. I. Fig. 32.; B, 

 Vol. I. Fig. 33., Zillerthal, Salzburg; C*, Vol. 



1. Fig. 34; Ti, Vol. I. Fig. 35. 

 Char, of Comb. Tessular. 



Combinations. 1. H. O. Vol. I. Fig. 3 & 4. Gulsen. 



2. O. D. Sweden. 3. H. O. D. Piedmont. 

 4. O.D.C a. Vesuvius. 5.O D. Az.B. Ziilerthal. 

 6. O. D. Aa. C. Ti. Zillerthal. 



Irregular forms, grains. 



Cleavage, octahedron, in some varieties perfect and 

 easily obtained, in others entirely obliterated by 

 conchoidal fracture. Fracture conchoidal, un- 

 even. Surface, the dodecahedrons commonly 

 streaked parallel to their edges of combination 

 with the octahedron ; of the octahedral trigonal- 

 icositetrahedron smooth, though curved ; the sur- 

 face of all the other forms is smooth. 



Lustre metallic, in some varieties imperfect. Co- 

 lour iron-black. Streak black. Opake. 



Brittle. Hardness = 5-5 ... 6-5. Sp. Gr. = 5-094, 

 octahedrons imbedded in chlorite. 



Compound Varieties. Twin-crystals : axis of re- 

 volution perpendicular, face of composition parallel 

 to a face of the octahedron, Fig. 156. Massive : 



