56 NEW YORK STATE MUSEUM 



extended across the ore body and was excavated previous to the 

 writer's visit. Most of the material collected from the dump heaps 

 also showed evidence of the same vug formation. 



MINERAL SPECIES 



Molybdenite 



Molybdenite occurs closely associated with brown titanite in 

 one of the smaller vugs opened on the 800 -foot level close to no. 5 

 shaft. The specimen obtained showed one bent and distorted 

 crystal about 10 mm in diameter as well as several smaller ones, 

 from which latter imperfect measurements were obtained which 

 served to establish the presence of the pyramid (2021). This 

 pyramid, as shown by Moses, ^ is of comparatively frequent occur- 

 rence on measurable crystals of molybdenite, being found on the 

 crystals from Frankford, Pa.; Aldfield, Quebec; Cape Breton, and 

 Okanogan county, Washington. The amphibole, titanite, phlogo- 

 pite and quartz associated with the Lyon Mountain molybdenite 

 showed marked evidence of partial resolution and were accom- 

 panied by secondary calcite, stilbite and pyrite. 



Pyrite 



Pyrite occurs abundantly in detached crystals of secondary 



origin associated with the orthoclase, hornblende, quartz and 



■ 

 magnetite of the wall rock in the contact zone with the ore body. 



They consist of small but brilliant individuals averaging about 



2 mm in diameter, the principal faces of which yield excellent 



reflections. 



The examination of a large number of these failed to reveal any 



new or unusual forms, the prevailing habit being that shown in 



figure I which is identical with that found on the pyrite from 



Kingsbridge.^ The occurring forms are a (no), (m), e (210), 



5 (321) and n (211), the two latter being present only as narrow 



faces. 



Quartz 



Quartz of both primary and secondary derivation occurs abund- 

 antly in the contact zone. The primary quartz occurs in rounded 

 masses of variable size deeply furrowed and completely covered 



iMoses, A. J. Crystallization of Molybdenite. Am. Jour. Sci. 1904. 167: 359. 



2Moses, A. J. Pyrite crystals from Kingsbridge. Am. Jour. Sci. Ser. 3. 1893. 45:488. 



