22 ECONOMICAL MINERALOGY. 



hundred miles. Throughout this whole extent, the ore is tolerably uniform in its character, 

 and differs in value chiefly in consequence of variations in the proportions of foreign matters 

 with which it is mixed. There are very few cases in which positively injurious substances 

 occur. The deposits usually have a northern and southern direction, and are parallel with, 

 and not at right angles to, the strata in which they occur. Whether their formation has been 

 cotemporaneous with that of the rocks in which they occur, whether they have been separated 

 by chemical affinity during the process of consolidation, or by electric agency, are questions, 

 the discussion of which does not properly belong to this department. 



I shall defer some general remarks concerning the manufacture of iron, until I have com- 

 pleted my account of the remaining ores of this metal. 



Magnetic Iron Sand. 



This variety occurs in the form of small crystals, or fragments of crystals, or in grains 

 constituting a sand. It is usually of a dark bluish black, or iron black colour, is strongly 

 attracted by the magnet, and may thus be completely separated from the earthy matters with 

 which it is mixed. It is often found to contain oxide of titanium, chromium, and it is frequently 

 associated with grains of garnet. 



Some New-York localities of iron sand have already been given in the preceding account 

 of the magnetic oxide. It maybe useful, however, to bring together all the information that 

 we possess, in regard to this variety. 



We are informed by Mr. Mather, that magnetic iron sand is found in small quantities along 

 the whole coast of Long Island, where the surf beats the shore. In some localities, there 

 are layers of it two or three inches thick. It is most abundant after storms. 



The same substance is found on the banks of the Hudson near West-Point, and on the 

 banks of many of the streams in the Highlands. It also occurs in great abundance at Port 

 Henry and elsewhere on Lake Champlain ; on the shores of Lake Ontario, in Monroe county ; 

 on those of Geneva lake and Lake Erie ; and on the banks of the Moose river, at Lyondale, 

 in Lewis county. It is sometimes in such abundance as to be used by the iron smelter. 



In regard to the occurrence of this sand, it may be observed that the theory commonly 

 received is, that it is the result of the disintegration of rocks which are contiguous, and which 

 abound in crystals of magnetic iron. This is said to be the case at West-Haven in Connecticut, 

 where it occurs on the beach which forms the margin of the seashore, while contiguous to 

 the beach is a formation of chlorite slate, abounding with minute crystals of magnetic iron. 

 These crystals, liberated from the slate, and broken by the action of the waves, constitute 

 the magnetic sand of the beach.* Now although the explanation here given may be applicable 

 to this locality, it can hardly be considered as generally applicable. The iron sand is fre- 

 quently found at a great distance from known beds of magnetic ore, and moreover its chemical 

 composition is oftentimes so very peculiar, that it is impossible to account for its occurrence 

 in the mode just described. 



* Silliman. CUaveland's Mineralogy, Second Edition. 



