Alt IX.], Watson, Manganese Ore- Deposits of Georgm. 197 



pit and cut, shaft and tunnel work are employed. These are 

 often used together, to adv^antage, in the same place, especially 

 where the ores begin at or near the surface and continue irregu- 

 larly to some depth below. In such cases, open pit and cut 

 work is used, and, from the bottom of the open work, shafts 

 are sunk and drifts are run at different levels from the shafts. 

 Tunneling becomes necessar\- in most of the steeper slope-de- 

 posits. In the lower de])osits, especially those of the valley- 

 bottoms, shafting and tunneling is most advantageously em- 

 ploN'ed. In most cases of tunneling and shafting it becomes 

 necessary, from the nature of the clays, to timber the openings 

 in order to prevent caving. The timbering over most of the 

 Georgia area has been poorly done, and, in many cases, put in 

 to meet only temporar}' needs. 



Expensive and heavy machinery is unnecessary, and the 

 equipment should be as light and portable as possible, so that 

 moving from one place to another, as the ore becomes exhaust- 

 ed, can be done speedily and at a small cost. 



P)eparatio)i of the Ore. 



The occurrence of the ores in the residual clays means, usu- 

 all)-, more or less admixture of the ore with clay. Usually, the 

 onl}' treatment of the ore necessary before shipping is to free it 

 from the adiiering clay. Crushing and jigging are necessary in 

 ihe spong)' or porous t}'pe of ore, the numerous cavities of 

 which are filled with the clay ; also in those ores containing con- 

 siderable free-quartz grains and cemented fragments of the rock. 

 This is especially true of much of the breccia-ore, which is ren- 

 dered marketable by materiall)- reducing the amount of siliceous 

 material in this method. Washing will usually suffice for cleans- 

 ing the bulk of the ore. In the crushed and jigged ore, subse- 

 quent washing is also necessar)-. 



In the early history of the manganese mining in Georgia 

 less care was used in properly cleansing the ore than at present, 

 and much of the ore then .shipped contained large quantities of 

 adhering clay and other extraneous material. The principal 

 and, frequentl}', the only treatment was that of screening. At 



