ECONOMICAL MINERALOGY. 



ORES OF IRON. 



MAGNETIC OXIDE OF IRON. Cleaveland. 



Per Oiidul^. Hauy. — Octahedral Iron Ore. Black or Magnetic Iron Ore. Jameson. — Magnetic Iron Ore. Thomson and 

 Dana. — Octaedrisches Eisen Erz. Mohs. — Oxidulaled lion. Phillips. — Aimant. BeudarU. — Magnetic Iron. Shepard. 



Description. Colour usually iron black, but sometimes bluish or steel grey. Powder 

 always nearly or quite black. The pure ore, when reduced to powder, is attracted by the 

 magnet. Some specimens also possess polarity. This property, so far as my observations 

 extend, belongs to those varieties which have a crystalline or foliated structure, and does not 

 appear to be much influenced by their purity. 



Primary form a regular octahedron. Frequently all the edges of the octahedron are replaced 

 by tangent planes. When these secondary faces become so much enlarged as to efface the 

 primary planes, the crystal assumes the form of the rhombic or garnet dodecahedron. Some- 

 times also the angles of the octahedron are truncated, but rarely to such an extent as to form 

 the cube. 



The following crystalline forms occur in this State : 



Fig. 1. 



Fi|f. 2. 



Fig. 3. 



O'Niel Mine, Orange County. 



Part I. 



O'Niel Mine, Orange County. 



O'Niel Mine, Orange County. 



