38 The American Geologist. juiy, i9oi. 
ed, and closely resem])ling- those of the mineral baux- 
ite? In other words, is not what is called liauxite 
in some localities diaspore or j;'ih1)site in a different ohys- 
ical state? Or; whether the commonly accepted formula for 
bauxite, AL().,.2H20 or Al(OH);,, must be modified according 
to locality to correspond to mono- di- or tri-hydrate as the case 
may be; and the general formula to be applied irrespective of 
locality and in its broadest usage, written Al/).,,.nHoO, in 
which II is variable and may correspond to one, two or three 
molecules of water. 
Origin of flic Ban.vifc Dc/^osifs. 
The Georgia bauxite deposits have been studied in consid- 
erable detail by Spencer and Hayes and the theories advanced 
by them to explain the accumulation of the ore-bodies are dis- 
cussed below at some length. 
Dr. J. W. Spencer* suggested the following theory to ex- 
plain the accumulation of the Georgia deposits : 
"This is an open question. Its situation along with the iron 
and manganese ores in dolomites suggests a common genesis. 
The formation skirts the crystalline rocks of central Georgia, 
whence the materials were originally obtained. Prof. Branner 
says that the Arkansas bauxite, although in Tertiary rocks, is 
located near eruptive syenites, or hornblende granites. Such 
rocks in Georgia have given rise, in part, to the iron and 
manganese minerals. The feldspar, in others, contains the 
aluminium, and there remains only the necessary solvent to 
transport and deposit it as the mineral bauxite."' 
'Tn the weathering of the rocks carbonic and vegetable acids 
remove the iron, manganese, lime, etc., from the hornblende, 
and potash and soda from the feldspar. So also carbonic acid 
in water can dissolve small quantities of alumina ; thus the same 
waters can remove the iron, manganese and alumina. The al- 
kalies derived from the decay of feldspars can also dissolve the 
alumina. Thus transported, the alumina may be precipitated in 
the lagoons in which the ferruginous and manganiferous cla}-ev 
limestones wer^ being formed. The white clays associated 
with the bauxite and iron ore deposits are usually of fine text- 
ure, indicative of deposition in quiet waters. The frequent re- 
*The Paleozoic Group of Georgia, Geological Survey ol Georgia, Atlanta, 
1893, pp. 225-226. 
