ECONOMICAL MINERALOGY 
ORES OF IRON. 
MAGNETIC OXIDE OF IRON. Cleaveland. 
Fer Oxidule. Hauy. — Octahedral Iron Ore. Black or Magnetic Iron Ore. Jameson. — Magnetic Iron Ore. Thomson and 
Dana. — Octaedrisches Eisen Erz. Mohs. — Oxidulated Iron. Phillips. — Aimant. Beudant. — 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. I. 
Fig. 2. 
Fig. 3. 
