IRON ORES OF NEW YOEK 529 



IRON ORES OF NEW YORK. 



By John C. Smock, revised by F. J. H. Merrill. 



The ores of iron, which occur in beds and deposits of workable 

 size in the State of New York, may be classified, according to 

 their chemical composition, into oxides and carbonates of iron, 

 and these classes ma}'' be subdivided, following the mineralogical 

 characters, into the several species and varieties. The following 

 tabular arrangement shows the natural grouping of species in 

 these two great divisions : 



Chemical Groups. Mineralogical Species and Common Names. 



f Red Hematite. 

 | Specular Ore. 

 f Anhydrous Ferric Oxide. Hematite -J 

 Sesquioxide of iron. j Clinton Ore. — Fossil ore. 



[Red Ochre. 



Ferric and Ferrous Oxides. f Magnetic Iron Ore. 



Oxides ■{ Magnetite ■{ 



Proto-sesquioxide of iron. (__ Titanif erous Iron Ore. 



f Brown Hematite. 

 Hydrated Ferric Oxide. Limonite-( Brown Ochre. 

 [ Sesquioxide of iron. [ Bog Iron Ore. 



Sideritef Carbonate0re - 



f Ferrous Carbonate. Snaihir"* Clay Iron Stone. 



Carbonates *! , 



L Carbonate of Iron. lron ore [ " White Horse. " 



A general law of occurrence of iron ores is that certain ore 

 species occur in, or are characteristic of, definite geological hori- 

 zons. For example, the magnetic iron ores are found in the 

 crystalline rock areas of the Precambrian ; the red hematite 

 appears to mark the Huronian ; the fossil ore, the limonite or 

 brown hematite are found in the Palaeozoic rocks; and the 

 carbonate and the bog iron ore in the more recent formations of 

 Tertiary and Post Tertiary ages. There are, as might be expected, 

 many exceptions ; but in the greater number of these appa- 

 rently exceptional cases, the surface alteration, due to weather- 

 ing or other atmospheric agencies, explains the occurrence. 



This relation between the geological formation and the 

 mineralogical species or hinds of iron ore indicates the areas in 

 which they may occur, and determines roughly their limits. 

 Hence, a geological map of the State shows approximately correct 



