28 ECONOMICAL MINERALOGY. 



yield from 33 to 35 per cent of metallic iron, which, however, is brittle, and is employed only 

 for large castings. By mixture with bog iron, or the magnetic oxide, a better result is ob- 

 tained. " This ore requires a high heat for melting, and it consumes one third more of char- 

 coal than the heirder ores. There is always produced a considerable quantity of carburet of 

 iron, in thin bright scales or leaves, exactly resembling plumbago."* 



It may be stated that this ore, and the rock immediately associated with it, often contain 

 nodules of massive and crystallized sulphate of barytes of a flesh red colour. The crystalline 

 forms, sometimes highly modified, are not, in any specimens which I have seen, sufficiently 

 perfect to be accurately projected. 



The following are the results of an analysis of a specimen of the lenticular clay iron ore 

 from Wolcott : 



Peroxide of iron, 51.50 



Carbonate of lime, . 24. 50 



Carbonate of magnesia, 7.75 



Silica, 6.00 



■' Alumina, .7.50 



Moisture and loss, 2.75 



Several localities of this ore occur in the County of Monroe ; but it is nowhere, I beheve, 

 converted to use in the process of reduction. At Rochester, a stratum of about a foot in 

 thickness is observed at the Lower falls, and from thence specimens of ordinary purity may 

 be obtained. It is entirely similar in its external characters to the ore from other localities. 

 The following is. its composition : 



Peroxide of iron, ...,. 42.93 



Carbonate of lime, 28.33 



Carbonate of magnesia, 10.40 



Silica and alumina, 17.66 



This ore has not been found, between the Genesee and Niagara rivers, in a regular stratum. 

 It may, perhaps, be found again west of the latter streanl. 



The preceding are the principal localities of the specular oxide of iron heretofore found in 

 tliis State. In point of abundance, it cannot be compared with -the magnetic oxide, nor is it 

 equal to that ore in purity. It, however, yields an iron which is highly valued for various 

 purposes, especially for castings ; and when mixed with other ores, it greatly improves their 

 quality. 



Dr. G. W. Boyd. New-York Geological Revorts, 1833. 



