536 ^V. A. NELSOX APPALACHIAN BAUXITE DEPOSITS 



Hayes's theory of the origin and mode of occurrence of the Appa- 

 lachian bauxite deposits has been considered correct by Watson/*^ who 

 studied the Georgia deposits in 1904. 



As before stated, Watson recognized that the bauxite deposits were 

 formed during a period of baseleveling, and considered the age of this 

 old peneplain to be Eocene. Shearer^^ follows Watson and considered 

 the north Georgia deposits to have been formed near the surface during 

 a period when the land was nearly baseleveled, and states this condition 

 existed during Eocene time. Ashley^^ considers the Chattanooga de- 

 posits to be of the same type as the Alabama-Georgia deposits, and to be 

 an extension of this field, and that the Chattanooga deposits all occur at 

 approximately the same elevation, but ends in stating that much more 

 extended studies of the Tennessee deposits will be necessary to determijie 

 which theory is correct in accounting for their origin and method of 

 formation. 



Laboratory Experiments 



On boiling both the bentonite from Bragg's quarry and the bauxite 

 from the Isabella Stewart mine with a sulphuric acid, in accordance with 

 the "Xational method," it is seen from the analyses given on pages — 

 and — that practically all the aluminum goes into solution. The 

 "Xational method'^ is as follows : 



"Boil for three hours with reflux condenser 2 grams of sample (finely 

 ground ) in 20 cubic centimeters of exactly 50 per cent sulphuric acid ; solu- 

 tion is then diluted with a little hot water and filtered; the residue is re- 

 ported as 'insoluble.' The filtrate is received in a 200-cubic-centimeter vol- 

 umetric flask, diluted to the mark, an aliquot portion taken out and prt'cipi- 

 tated with ammonia in the usual manner, precipitate ignited and weighed as 

 ALO3 plus FeaOg. Another aliquot portion is removed, on which iron is deter- 

 mined (volumetrically or colorimetrically ) and calculated to FcoOs. (Al.,Ov 

 plus FeaOs) — FCaOs equals AI2O3." 



The results obtained by treating the two minerals in this manner are 

 as follows : 



^•> Thomas H. Watson: Bauxite deposits of Georgia. Georgia Geol. Survey. 190 4. p. 

 12(5. 



11 H. K. Shearer : Bauxite and fullers' earth of coastal plain of Georgia. Georgia 

 Geol. Survey. Bull. 31. 1017. p. 23. 



1- George H. Ashley : Bauxite mining in Tennessee. Tennessee fxeol. Survey. Resources 

 of Tennessee, vol. i. 1011. pp. 211-210. 



