178 DESCRIPTIONS OF MINERALS. 



and the same is found in Pennsylvania and south to Alabama, 

 and also in "Wisconsin ; it contains 50 per cent, of oxide of 

 iron, with about 25 of carbonate of lime and more or less 

 magnesia and clay. The coal region of Pennsylvania affords 

 abundantly the clay iron ores, but they are mostly either the 

 argillaceous carbonate or limonite. 



Valuable as an iron ore, though less easily worked when 

 pure and metallic than the magnetic and hydrous ores. Pul- 

 verized red hematite is used for polishing metal. Bed chalk 

 is a well-known material for red pencils. 



Menaccanite — Dmenite. Titanic Iron. Washingtonite. 



Ehombohedral. BaE = 8o° 31'. Often in thin plates or 

 eeams in quartz ; also in grains. Crystals sometimes very 

 large and tabular. 



Color iron-black ; streak submetallic. Lustre metallic or 

 submetallic. H. =5-6. G. =45-5. Acts slightly on the 

 magnetic needle. 



Composition. Like that of hematite, except that part of 

 the iron is replaced by titanium ; the amount replaced is 

 very variable. Infusible alone before the blowpipe. 



biff. Xear specular iron, but its powder is not red. 



Obs. Crystals, an inch or so in diameter, occur in War- 

 wick, Amity and Monroe, Orange County, X. Y. ; also near 

 Edenville and Greenwood Furnace ; also at South Eoyalston 

 and Goshen, Mass. ; at "Washington, South Britain, and 

 Litchfield, Conn. ; at Westerly, Rhode Island. 



It is of no value in the arts and is a deleterious constitu- 

 ent of many iron ores. 



Magnetite.— Magnetic Iron Ore. 



Isometric. Often in octahedrons (fig. 1), and dodecahe- 

 drons (fig. 2 ). Cleavage octahe- 

 dral ; sometimes distinct. Also 

 granularly massive. Occasionally 

 in dendritic forms between the 

 folia of mica. 



Color iron-black. Streak black. 

 Brittle. H. =5 -5-6 -5. G.= 50 

 -51. Strongly attracted by the 

 magnet, and sometimes having polaritv. 



Composition. Fe£e 4 =Fet) + Fe 0" 3 = Oxygen 27-6, iron 



