182 The American Geologist. March, 1891 
The Arkansas beds occur near the railway in the vicinity of 
Little Rock, Pulaski county, and near Benton, Saline county. 
The exposures vary in size from an acre to twenty acres or more, 
and aggregate something over a square mile. This does not, in 
all probability, include the total area covered by bauxite in the 
counties mentioned, for the method of occurrence of the deposits 
leads to the supposition that there ai'e others as yet undiscovered 
by the survey. 
In thickness the beds vary from a few feet to over 40 feet, with 
the total thickness undetermined ; the average thickness is at least 
15 feet. 
These Arkansas deposits occur only in Tertiary areas and in the 
neighborhood of eruptive S} T enites ("granites") to which they 
seem to be genetically related. In elevation they occur only at 
and below 300 feet above tide level, and most of them lie between 
260 and" 270 feet above tide. They have soft Tertiary beds both 
above and below them at a few places and must therefore ba of 
Tertiary age. As a rule, however, thej r have no covering, the 
overlying beds having been removed by erosion and are high 
enough above the drainage of the country to be readily quarried. 
Erosive action has removed a part of the bauxite in some cases, 
but there are, in all probabilit}', many places at which it has not 
yet been even uncovered. 
It is pisolitic in structure, and, like all bauxite, varies more or 
less in color and in chemical composition. At a few places it is 
so charged with iron that attempts have been made to mine it for 
iron ore. Some of the samples from these pits assaj* over 50 
per cent, of metallic iron. This ferruginous kind is exceptional, 
however. From the dark red varieties it grades through the 
browns and 3 r ellow to pearl gra}', cream-colored and milky white, 
the pinks, browns and grays being the more abundant. Some of 
the white varieties have the chemical composition of kaolin, 
while the red, brown and gray have but little silica and iron, 
and a high percentage of alumina. The analyses given below 
show that this bauxite is as good as that of France, Austria, and 
Ireland, for the manufacture of chemical products, for refractory 
material and for the manufacture of aluminum by the Deville pro- 
cess. Should there be a market in this country for such material 
Arkansas will be able to supply an}- demand that may be made for 
