ECONOMIC GEOLOGY 219 



in operation in 1801 and 1802, and they were run upon the ores 

 in their vicinity. But the output was small, in the aggregate a 

 few thousands of tons. The rapid increase was after 1840. 



THE HEMATITE ORES OF ST LAWRENCE AND JEFFER- 

 SON COUNTIES 



The hematites., or red hematites', as distinguished from the 

 brown hematites (limonites) are mined in a narrow belt, scarcely 

 30 miles long, stretching from Philadelphia, in Jefferson county, 

 northeast into Hermon, in St Lawrence county. The ore de- 

 posits are found associated with a so-called serpentine rock, and 

 lying between the Potsdam sandstone and the crystalline rocks 

 of the Archaean age. 



The hematite of these mines is generally firm and massive, of a 

 deep red color, soiling whatever it touches. In some of the mines 

 there is a specular ore, which has a crystalline structure, metallic 

 lustre and is of a steel-gray to black color. Calcite, carbonate of 

 iron, ferruginous quartz, pyrite and millerite occur in the ore. 

 These 'ores average from 48 to 53% of metallic iron. They con- 

 tain an excess of phosphorus above the limit demanded by furnace 

 managers for making Bessemer iron. For mixing with more re- 

 fractory ores they are sought after, being almost self-fluxing. In 

 the market they are often known as ' Antwerp red hematites ' and 

 ' Rossie hematites.' 



Charcoal furnaces were built early in this century at Rossie, 

 St Lawrence county, and at Sterlingville and Antwerp, in Jeffer- 

 son county, for smelting these ores. 



THE CLINTON OR FOSSIL ORES 



The red hematite of the Clinton group bears several names; 

 from its aggregated grains it is termed ' oolitic ore ' or 

 ' lenticular iron ore; ' from its fossiliferous character, it is widely 

 known as ' fossil ore,' and from its place in the geological series, 

 it is often called ' Clinton ore. 5 It is remarkable for the thin, yet 

 persistent beds 'over wide areas^ which lie between green shales 

 and calcareous strata. Following the outcrop of the Clinton 

 group, the ore has been found in Herkimer, Oneida, Madison, 



