IRON. 383 



Under these circunstances, the specimen almost always contains a small proportion of nickel 

 or chromium. In a few cases, however, native iron of undoubted terrestrial origin has been 

 found. Such are the varieties from Canaan, Connecticut, and from Guilford in North Caro- 

 lina ; the latter of which consists of a single octahedral crystal, now in the Cabinet of Yale 

 College, weighing seven ounces, and which is said to have been detached from a mass weigh- 

 ing twenty-eight pounds.* 



LOCALITIES. 



Otsego County. In the cabinet of the Albany Institute, there is a specimen labelled 

 " Native Iron from Burlington," in this county. It was received from Prof. J. Hadley, but I 

 know nothing further of its history. It is malleable, and has a blackish coating. 



Yates County. Mr. T. G. Clemson has described a specimen of what he called native 

 iron, found near Penn-Yan. It was represented as being from a larger mass found in a sand- 

 stone rock. It acted on the needle, was free from oxides, and contained a minute portion of 

 carbon, but neither nickel nor cobalt could be detected in it.t 



MAGNETIC IRON ORE. 



[In allusion to its magnetic properties.] 



Fcr Oiidule. Haiiy. — Magnetic Oxide of Iron. Cleaveland. — Octahedral Iron Ore, Black or Magnetic Iron 

 Ore. Jamcscm. — Magnetic Iron Ore, Tlwmson and Dcuna, — Octaedrisches Eisen-Erz. Moks, — Oxidulated 

 Iron. Phillips. — Aimant. Beudant. — Magnetic Iron. Shepard. 



Fig. 437. Description. Colour usually iron-black, but sometimes bluish 



#or steel-grey. Streak always nearly or quite black. It occurs re- 

 gularly crystallized ; also in grains, massive and disseminated. The 

 primary form is a regular octahedron. Fig. 437. Cleavage parallel 

 with the primary. Fracture uneven or conchoidal. Lustre metallic. 

 Opaque. Brittle. Hardness from 5.5 to 6.5. Specific gravity 

 from 4 . 74 to 5 . 20. It is attracted by the magnet, and sometimes 

 exhibits polarity. Infusible by the blowpipe alone, but becomes 

 brown, and loses its magnetism. With borax, in the oxidizing 

 flame it fuses into a dull red glass, which becomes clear on cooling, 

 and often assumes a yellow tint ; in the reducing flame, it becomes bottle-green. Insoluble 

 in nitric acid, but usually soluble in hot concentrated muriatic acid. Sometimes, however, 

 it is necessary to calcine the ore with carbonate of potash or soda, before its solution can be 

 effected. The black colour of its powder, and its strong action upon the magnet, will usually 

 serve to distinguish this species from the specular iron ore which it often resembles. 



• Shepard. Treatue on Mineralogy. II. 70. f Tnuuactions of tlie Geological Society of Pennsylvania. I. 358. 



