INTRODUCTION. 



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 may be subdivided, following the mineralogical characters, 

 into the several species and varieties. The following tabular arrange- 

 ment shows the natural grouping of the species in these two great 

 divisions : 



Note. Pyrite and Pyrrhotite, known commonly as iron pyrites and magnetic 

 pyrites, menaccanite or titanic iron and other compounds of iron, some of which 

 are found in large deposits, or are widely distributed, are not put in this table, 

 because they cannot be used economically as sources of iron. 



Chemical Groups. 



f Anhydrous Ferric Oxide. 

 I Sesquioxide of Iron. 



Mineralogical Species and Common Names. 



Hematite ■{ 



f Red Hematite. 

 Specular Ore. 



Oxides ■{ 



Ferric and Ferrous Oxides. 

 Proto-sesquioxide of Iron. 



Clinton Ore. — Fossil Ore. 

 [Red Ochre. 



f Magnetic Iron Ore. 



Hydrated Ferric Oxide. 

 Sesquioxide of Iron. 



(Ferrous Carbonate. 

 Carbonates J. 



[ Carbonate of Iron. 



Magnetite <j 



^Titaniferous Iron Ore. 



f Brown Hematite. 

 Limonite -j Brown Ochres. 

 ^ Bog Iron Ore. 



Siderite | rCarbonate0l ' e - 

 Spathic «j Clay Iron Stone. 

 Iron 0re L" White Horse." 



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

 occur in, or are characteristic of, definite geological horizons. For 

 example, the magnetic iron ores are found in the crystalline rock areas 

 of the Laurentian series ; the red hematite appears to mark the 

 Huronian ; the fossil ore the Clinton epoch ; the limonite, or brown 

 hematite the formations of the Trenton Period ; the carbonate the 

 Marcellus shale, and the bog iron ore the more recent formations of 

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



* See paper by the author in Trans, of Am. Inst. Mm. Eng., Vol. xii, pp. 130, 

 et seq. 



