8 ECONOMICAL MINERALOGY. 



McFarlane tract. It has not been extensively wrought, althougli there are evidences of an 

 abundant deposit. The ore is strongly magnetic, possesses polarity, and is remarkable for the 

 ease with wliicli it cleaves in the direction of the primary octahedron. Large cleavage crystals 

 may be obtained. Associated with the ore are mica, hornblende, pyroxene, magnetic and 

 common iron pyrites. 



The following are the results of my analysis of a specimen of this ore, which had the 

 octahedral cleavage and an iron black colour : 



Protoxide and peroxide of iron, 96.50 



Silica and alumina, 3.50 



Forshee Mine. This is an extensive bed of magnetic iron ore, about a quarter of a mile 

 southwest of the O'Niel Mine. The whole hill, which is more than a quarter of a mile in 

 length and nearly as much in width, appears to consist of alternate layers of rock and ore, 

 the latter forming a large proportion. The general direction of the deposit is nearly north 

 and south. Some of the layers of ore have a compact structure, while others are made up of 

 what is called sJiot ore, often quite free from iron pyrites. Rarely it is found crystallized in 

 the form of octahedrons. In some parts of the mine, the ore has a cavernous or celhdar 

 structure, as if some of the original constituents had undergone decomposition and been dis- 

 solved out. This form of ore passes into an earthy oxide of iron, having a dark brown colour, 

 and closely resembling umber. 



The following is the composition of the cellular variety of the magnetic oxide of iron from 

 tlris mine : 



Protoxide of iron, 44. 10 



Peroxide of iron, 52. 75 



Silica and alumina, 3.15 



Oxides of titanium and manganese, traces. 



The constituents of the umber, according to my analysis, are as follows, viz : 



Peroxide of iron, 68. 00 



Peroxide of manganese, 8. 50 



Silica and alumina, 6.50 



Water, 17.00 



The last, therefore, is a liydrous peroxide of iron, and is undoubtedly the result of the 

 decomposition of iron pyrites. 



Associated with the iron ore at tliis mine, are delicate veins of amianthus, red garnet, brown 

 tremolite, calcareous spar, serpentine and mica. 



It may be added, that the ore from the Forshee Mine is highly valued by the iron masters 

 in this part of the State, especially those portions of it which are granular and cavernous. 

 The latter variety is sufficiently free from iron pyrites to be used without the preliminary 

 operation of roasting. 



