114 NEW YORK STATE MUSEUM 



ticularly noticeable on weathered outcrops where the narrow bands 

 of magnetite stand out in relief like small veins. The magnetite 

 occurs in granular particles, or irregular masses made up of many 

 grains, with rarely any tendency toward crystal development. 

 When specimens are examined under the microscope the particles 

 are seen to occupy the interspaces, occurring on the borders of the 

 other minerals or completely inclosing them, a relation which 

 suggests that they have been the last to form. A few small crystals 

 of magnetite having octahedral boundaries are generally observed 

 in the slides and are doubtless of an earlier generation. In the 

 average ore there are about equal proportions of magnetite and gan- 

 gue minerals. Among the less important components of the ore 

 may be mentioned apatite, titanite, zircon and pyrite; they con- 

 stitute only a minute percentage of the mass as shown by the 

 analyses. At the Williams pit, a black almost opaque garnet was 

 found in the form of rounded grains mingled with magnetite, near 

 the contact of the ore body and the schist of the hanging wall; 

 this mineral has not been observed elsewhere. 



Pegmatite is abundant in the ore bodies. The common variety 

 has a reddish color and is composed of alkali feldspar, augite, 

 quartz and magnetite, resembling the augite gneiss except for its 

 coarser more massive texture. Occasionally it contains a sufficient 

 quantity of magnetite to be considered an ore. Another variety 

 of pegmatite is made up of deep red crystals of microcline with 

 plagioclase, scapolite, augite, hornblende, epidote, quartz and 

 magnetite. The epidote is partly an alteration product of the 

 plagioclase feldspar which is probably oligoclase. The pegmatite 

 occurs in bodies that rarely possess any regularity of outline like 

 dikes, though this may be due to the squeezing and shearing 

 it has undergone. Large interlocking masses of hornblende and 

 augite anhedra occur in both varieties of pegmatite. During 

 the course of mining operations vugs and cavities are frequently 

 opened within the pegmatite masses and some have afforded 

 remarkable groups of well crystallized minerals. 



Distribution of the deposits 



The ore bodies which have been mined on a commercial scale 

 lie within a narrow belt extending northeast and southwest along 

 the eastern edge of the valley. They have been proved by mag- 

 netic attraction and borings to constitute a nearly continuous 

 scries with a linear extent of some 5 miles. The several openings 

 jn the belt comprise mine 81 on the southern extremity, the main 



