THE MINING AND QUARRY INDUSTRY 9I 



The Lyon Mountain ore bodies are low grade biit of unusual size. 

 They may be described as impregnated zones in the country rock 

 of the region, which is a light cotored augite gneiss varying from the 

 composition of granite to that of syenite. The zones are of sheet- 

 like or tabular form and have a northeast-southwest strike in con- 

 formity with the gneiss. Their outcrop extends along the northern 

 slopes of the mountain at an elevation of about 2000 feet. 



The ore bodies are remarkable for their regularity as well as their 

 continuity along the strike and on the dip. From shaft 16 near the 

 present mill openings have been made at frequent intervals south- 

 west to the Burden mine, a distance of over 3500 feet. In this sec- 

 tion, two and in one place three parallel ore bodies have been found. 

 Immediately northeast from slope 16 the deposit has not been worked, 

 though its existence has been established by magnetic observations, 

 while 2500 feet distant from this point is mine 82 where the first ore 

 was mined. The Parkhurst mine, which appears to be on the same 

 ore zone, lies over 2 miles northeast of mine 82. 



Throughout most of its extent, the deposit shows little disturb- 

 ance, the outcrop follows an almost straight line and the walls are 

 smooth and evenly spaced. There is no tendency to the formation 

 of lenticular ore bodies which are common in other districts of the 

 Adirondacks. On the southwestern end, however, the strike changes 

 rather abruptly to east and west, due to a fold, while the dip swings 

 around from northwest to north and becomes considerably flatter. 

 This change is accompanied by crumpling and minor folding in the 

 deposit. Between shaft 5, which approximately marks the axis of 

 the fold, and the Burden mine, the bounds of the deposit are not 

 well defined; the outcrop, however, shows a marked widening in 

 this part. 



Beyond the Burden mine the geologic structure is obscured by the 

 heavy drift deposits which cover the adjoining valley. The extent 

 of the deposit in this direction has not been definitely determined. 

 It is known that one or more ore bodies occur on a low hill to the 

 west, parallel to the main group, but their relation to the latter is 

 problematic. It seems improbable that the deposit should terminate 

 abruptly, except by faulting, and in this case its continuation may 

 be represented by the ore bodies just mentioned. 



The ore consists of a granular mixture of magnetite with feldspar, 



quartz, hornblende and augite. Mineralogically it resembles the 



gneiss wall rock, though of course much richer in magnetite. The 



average material as mined carries probably 50 or 60 per cent of this 



flineral, corresponding to 30 or 40 per cent rron. As a rule the 



