A. J. Moses — Crystallization of Molybdenite. 361 



4-. Molybdenite from Okanogan Co., Washington. 



Messrs. Geo. L. English & Co. permitted me to examine over 

 one hundred crystals from this locality. Many of these sug- 

 gested a pyramid approximately the (2025) found upon the 

 crystal from the Enterprise Mine, but the crystals were bent 

 and the faces bruised and rounded. Etch figures -J to l nim 

 across and six-sided in cross section were observed and upon 

 one crystal in which they were unusually distinct their parallel- 

 ism to the hexagonal outline of the crystal was shown by the 

 cross hairs of the microscope. This particular crystal also 

 showed three systems of fine lines parallel to the edges of the 

 cleavage in addition to a few coarse grooves perpendicular to 

 these edges. 



The best measurements were obtained from a crystal (fig. 3) 



l 

 2 



which distinctly showed two pyramids, the brighter being the 

 flatter form but the steeper form being more developed. The 

 crystal formed one of a group and only two zones could be 

 adjusted for measurement. The images were multiple but the 

 groups were small and the angles with the cleavage were : 



Zonel. 30° 17' and 41° 46' 



" 2. 29 32 Blurred 



Average 29° 54' 41° 46 



The nearest simple indices are (1014) (28° 51') and (2025) 

 41° 23'. If 41°_46 / be taken as the angle of the unit pyramid, 

 the pyramid (1014) would have an angle of 29° 10'. 



A crystal, bent like that figured by Knop so that the ridges 

 divided the cleavage into three areas not in the same plane, 

 yielded an angle of 76° 59' between a pyramidal plane and the 

 adjacent portion of the cleavage. 



For (2021) the angle 77° 13' has been calculated. 



5. Molybdenite from the Tilly Foster Iron Mine, Brewsters, N. Y. 



Mr. F. Y. Cruser presented the Egleston Museum with some 



specimens of molybdenite found by him at the mine. They 



occur in a cleavable calcite associated with small bright crys- 



