IKON ORES. 



239 



Uses. Valuable as an iron ore, though less easily woiked 

 when pure and metallic than the magnetic and hematitic 

 ores. Pulverized red hematite is used tor polishing metals. 

 Red chalk is a well known material for red pencils. 



LIMONITE. BROWN IRON ORE. 



Usually massive, and often with a smooth botryoidal or 

 stalactitic surface, having a compact fibrous structure within 

 Also earthy. 



Color dark brown to ocher-yellow ; streak yellowish 

 brown to dull yellow. Luster sometimes submetallic ; oftei 

 dull and earthy; on a surface of fracture frequently silky 

 11=5— 5-5. Gr=3-6— 4. 



Varieties and Composition. The following are the princi- 

 pal varieties : 



Brown hematite. The botryoidal, stalactitic and associated 

 compact ore. 



Brown ocher, Yellow ocher Earthy ochreous varieties, 

 of a brown or yellow color. 



Brown and yellow clay iron stone. Impure ore, hard and 

 compact, of a brown or yellow color. 



Bog iron ore. A loose earthy ore of a brownish-black 

 color, occurring in low grounds. 



Composition when pure : peroxyd of iron 85*8, (seven-tenths 

 of which is pure iron,) and water 14*4 ; or it is a hydrous 

 yeroxyd of iron, containing when pure about two-thirds its 

 weight of pure iron. Before the blowpipe, blackens and be- 

 comes magnetic. Gives with borax in the inner flame a 

 green glass. 



Dif. This is a much softer ore than either of the two pre 

 ceding, and is peculiar in its frequent stalactitic forms, and 

 in its affording water when heated in a glass tube. 



Obs. Occurs connected with rocks of all ages, but ap- 

 pears, as shown by the stalactitic and other forms, to have 

 resulted in all cases from the decomposition of other iron ores, 

 probably the sulphuret. 



This is an abundant ore in the United States. The fol- 

 lowing are a few of its localities. Extensive beds exist at 

 Salisbury and Kent, Conn., in mica slate; also in the neigh- 



What i9 said of the uses of specular iron ? What is the appearance 

 of brown iron ore ? its composition I Describe its varie.ies. What 

 ore distinguishing characters ] How does this ore occur 1 



