BAUXITE. 19 



Bauxite. 



This ore, a Hydrate of alumina, is much used as a source of 

 the metal aluminum and of some of its compounds, mainly 

 alum. In this state it occurs, mainly in the Knox Dolomite 

 and in the Weisner Ouartzite formations, in irregular deposits 

 along a narrow belt extending from the Georgia line south- 

 westward as far as Anniston. All the deposits thus far known 

 are in the counties of Cherokee, Cleburne, Calhoun and De- 

 Kalb, but they are too irregular in their occurrence and have 

 been too little investigated to admit of any close approxima- 

 tion to the quantity of the ore. 



The ore is commonly concretionary or pisolitic though some- 

 times compact, homogenous and fine grained, and the best 

 quality is of gray to white colors. Much of it has iron oxide 

 replacing part of the alumina with the result of giving a red- 

 dish and mottled appearance to the ore. 



Associated with the true bauxite are mixtures of clay and 

 bauxite in varying proportions, and in places irregular streaks 

 or bands of pure halloysite occur in the midst of the bauxite. 

 The bauxitic clays above mentioned are exceedingly refractory 

 and have been suggested as suitable material for the manu- 

 facture of fire brick. 



The mode of ccurrence of the bauxite is very similar to that 

 of limonite, in irregular and ill defined pockets, and in some 

 of the limonite banks about Rock Run in Cherokee county, the 

 iron ore appears to grade into the bauxite, and both ores have 

 been obtained from the same digging. Other associations 

 with the bauxite are white china clay and lignite, both of which 

 occur in a bauxite-limonite bank near Rock Run. Manganese 

 ores have also been observed in connection with the bauxite. 



The bauxite is obtained from open cuts and pits which are 

 in places 60 to 70 feet deep. It is easily mined, being rather 

 soft below the surface. After sorting and concentrating by 

 screen and hand, it is spread out under shelter and dried by 

 artificial heat before sending to the market, rotary driers being 

 most commonly used. Only the very highest grade of the ore 

 is sold, the lower grades being thrown aside for the present, 

 but the time will probably come when it will all be used in the 

 manufacture of fire brick, as well as of aluminum compounds 



