10 Bulletin of the New York State Museum. 



and the ridge of lean ore at Little River, are almost inexhaustible, 

 and, with the advent of practicable, concentrating processes, all of 

 them can produce cheap ores and compete with other iron-ore districts 

 of the country. 



Ill -THE HEMATITE ORES OF ST. LAWRENCE AND 

 JEFFERSON COUNTIES. 



The hematites, or red hematites, as distinguished from the brown 

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

 miles long, stretching from Philadelphia, in Jefferson county, north- 

 east into Hermon, in St. Lawrence county. The ore deposits are 

 found associated with a so-called serpentine rock, and lying between 

 the Potsdam sandstone and the crystalline rocks of the Archaaan age. 

 The geological horizon appears to be below the Potsdam, and it is 

 probably Huronian, although it has not been so recognized by Dr. 

 T. S. Hunt in his references to * the hematites of Canada and North- 

 ern New York. The deposits are found to be very irregular in 

 shape, due apparantly to the way in which the " serpentine " rock 

 is mixed with the hematite, but their general structure is that of 

 stratified bodies. The cap rock is a sandstone ; the bottom rock, 

 slaty beds, underlain by a white, graphitic, crystalline limestone. 

 From the variations in the ore, as tested by borings with the 

 diamond drill at the Caledonia mines, it seems reasonable to assume 

 the existence of two classes of deposits — one, the originally stratified 

 sheets, and the other, secondary deposits in smaller and irregular 

 shaped pockets. 



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 lus- 

 tre 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 per cent, of metallic iron. They contain an 

 excess of phosphorus above the limit demanded by furnace managers 

 for making Bessemer iron. For mixing with more refractory ores 

 they are sought after, being almost self-fluxing. In the market they 

 are often known as "Antwerp red hematites" and " Rossi e 

 hematites." 



* " On the Mineralogy of the Lanrentian Limestones of North America," in the 

 21st Ann. Report of the Regents of the University of New York, Albany, 1871, pp. 



88-89. 



