46 NEW YORK STATE MUSEUM 



hematite is arranged in concentric layers. In each ore particle 

 may be recognized often a number of such layers. Their deposi- 

 tion has taken place at successive intervals while the grains were 

 moved about and in complete contact with the iron-bearing solu- 

 tions. The formation of oolitic limestone illustrates the general 

 conditions that must have prevailed during the deposition of the 

 ore. The second type of structure found in the Clinton ores is 

 distinguished by the occurrence of the hematite with an organic 

 form, due to its replacement of some calcareous fossil such as a 

 bryozoan, crinoid or brachiopod. The fossils may be wholly re- 

 placed, but more commonly a portion of the original lime is retained 

 in the interiors, and in some cases the change has not progressed 

 beyond the outer surfaces, so that practically all steps between fos- 

 siliferous limestone and ore may be observed. 



The two structures — fossiliferous and oolitic — ^are not infre- 

 quently found together, though in most samples from the New York 

 beds one type so prevails as to lend a fairly uniform appearance to 

 the ore. The oolitic structure is more limited in its development 

 than the other. It characterizes the main bed in the eastern section, 

 notably around Clinton and in the towns of New Hartford and 

 Westmoreland, and is found farther west in the ore at Brewerton 

 and Lakeport. The fossiliferous ore appears at Clinton in the so 

 called flux bed, and forms the single deposit in the town of Verona, 

 Oneida co. The ore mined at Sterling Station, as well as the entire 

 section throughout Cayuga and Wayne counties, belongs to that 

 type. 



A curious feature of the oolitic grains, that has been brought out 

 by C. H. Smyth jr, in his studies^ of the Clinton ores, is the presence 

 of amorphous silica . in intimate association with the hematite. 

 Though the silica layers are scarcely discernible in ordinary thin 

 sections, they are easily revealed by subjecting the grains to the 

 action of hydrochloric acid. When the hematite has thus been 

 removed in solution, there remains a perfect cast of the original 

 oolite preserved by the gelatinous, transparent silica. Apparently, 

 the deposition of the silica took place at the same time and from the 

 same solution as the iron. 



The individual spherules are usually closely compacted and often 

 coalescent on the borders. They are seldom more than i millimeter 

 in diameter. The quartz kernels in their interiors are scarcely half 

 that size as an extreme and range down to particles so minute that 



» Am. Jour. Sci. 1892. 143: 488. Also Zeits. fiir prak. Geol. Aug. 1894. 



