The Georgia Bauxite Deposits. — JVafson. 31 
Besides gibbsite, halloysite and kaolin, commercial deposits 
of brown iron ore and manganese oxides, mostly psilomelane 
and pyrolusite perhaps, are more or less intimately associated 
with the bauxite deposits and have been extensively mined in 
several localities. The deposits of brown iron ore and bauxite 
are found in direct contact with each other at several locali- 
ties in the district. 
Chemical Coinposition. 
While scores of reliable commercial analyses of the Georgia 
bauxite are available, ver}' little has been done toward working 
out the exact chemical constitution of this material or attempt- 
ing to establish the exact form in which it exists chemically. 
It has been generally assumed that the southern Appalachian 
bauxites, like most of the foreign material, correspond to the 
formula AloO.,.2H.O, the bi-hydrate of alumina. That the as- 
sumption, however, is not warranted by the facts is evident 
from ( I ) the easier solubility of the Georgia- Alabama bauxit* 
than that of the French ores; and (2) the uniformly lower 
percentage of AL,0.j and the proportionately higher percentage 
of combined water in the Georgia-Alabama ore than in the * 
French ores, as shown in the comparison of a large number of 
analyses of the ore from the two countries. This is made the 
more apparent from the soniewhat lengthy discussion which 
follows below. 
At present, three recognized hydrates of alumina occur in 
nature, namely, the monohydrate, Al./)...H^O, known as the 
mineral diaspore and containing, 
ALO, 85.0,'.' 
H.O 15. o;*; 
the dihydrate, Ak().,.2]rL.( ), which is the general formula* 
given for the mineral bauxite, containing, 
A1,0, 73-9;^ 
H,0 26.1^ 
and the trihydratc, AL,0.,.3H20, known as the minerals hy- 
drargillite and gibbsite. and containing, 
AFO, 65.4^ 
H,0 34.6;/ 
Roscoe and Schorlemmerf give the formula (Al.h^O-.O 
(OH )^ for bauxite, but this seems not to apply to the Georgia- 
*Dana, K. S.. a System of Mineralogy, 1893, Sixth edition, p. 2.51. 
tA Treatise on Chemistry, vol. i, p. -i**. 
