414 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213. 
In 1885 Radcliffe discussed the Saltville product as follows: 
A specimen of the rock salt sent by the superintendent of the salt works was 
brownish-red in color, with a crystalline structure, and was obtained while deep- 
ening one of the salt wells. This rock salt is not mined, the brine alone being 
used for the manufacture of salt. The capacity of the works is at present 450,000 
bushels per year, though at one time during the late war the yield was as high as 
10,000 bushels per day. According to analysis the rock salt contained— 
Per cent. 
Sodium chloride 93. 05 
Potassium chloride Trace. 
Calcium sulphate 2.40 
Magnesium sulphate .07 
Ferric oxide -• .83 
Silica 2.81 
Water .30 
An analysis of the marketed salt gave 98.89 per cent sodium chloride, with a 
small percentage of calcium sulphate, water, and a trace of magnesium sulphate, 
showing it to be a high-grade salt. 
At present the salt industry in the Ilolston Valley is entirely in the 
hands of the Matthieson Alkali Company. I 'art of the product is 
marketed as salt, while a Large proportion is utilized in the alkali 
plant of the company, located at Saltville. 
While it is probable that brines could be obtained by boring in 
other parts of the Ilolston Valley, no possible extension of the salt 
field could be so favorably located in regard to transportation routes 
as is the present producing area near Saltville, with the exception of 
the property near Plasterco. 
COMPARISON OF AMERICAN AND FOREIGN SALTS. 
Analyses of rock salt, brines, and commercial salt, from the Vir- 
ginia salt region follow. For comparison, a series of analyses of sim- 
ilar materials from other localities, both American and foreign, has 
been added. 
Most of the salt produced in the United States is obtained b} r pump- 
ing and evaporating brines from wells reaching down to beds of rock 
salt or to rock formations carrying much saline matter disseminated 
through their mass. Part of the remaining product is secured by 
mining and crushing rock salt, and part b} r evaporating ocean water 
or the waters of salt lakes. 
In point of geologic age, the oldest salt-bearing beds now actively 
worked in the United States and Canada occur in the Salina group, 
near the top of the Upper Silurian. Urines have been obtained, it is 
true, from the Medina formation of the Silurian in New York, but 
these have never been of much economic importance. The geologic 
horizons from which the salt of Ontario and the various States is 
obtained are shown below. 
"Mineral Resources U. S. for 1883-1884, p. 840. 
