282 A.J.Moses — Crystallization of Luzonite. 



The largest face in each crystal was undoubtedly c = 001, 

 but these faces were so striated that the series of images gave 

 values for p each side of the correct position through four or 

 five degrees, and probably involved various indeterminable 

 domes li I and li I. 



The remaining forms determined were t = 102 well devel- 

 oped; A = 112 minute but bright, and a new form,j9 = 214 

 occurring as a narrow truncation. 



The comparison between the measured and computed 

 coordinate angles for I, m, t, A andj? is: 





Measured. 





Calculated. 



^ace. 



e 



f 



i 



6 



p 



1 



67°36f 



90° 





67°34f 



90° 



m 



50° 15' 



90° 





50° 27*' 



90° 



t 



89° 52^ 



28° 



ioi' 



90° 



28° 3' 



A 



51° 58' 



34° 



10*' 



50° 531' 



34° 29' 



P 



68° 45' 



30° 



17' 



68° 6' 



30° 8{ 



Upon a few of the specimens there were small yellow 

 sphalerite crystals and small crystals of scheelite not suitable 

 for measurement. 



3. JVew Faces on Sylvanite Crystal from Cripple Creek, Col. 



Some three or four years ago Mr. F. C. Hamilton purchased 

 some telluride specimens from a dealer at Cripple Creek, Col., 

 and presented them to Columbia University. Among these 

 was a mass of 3-J- oz. in weight which consisted almost entirely 

 of large crystals and crystal bunches some of them 20 X 5 mm 

 in length and breadth. Nearly every one of these was partly 

 coated with a thin layer of chalcedony, but many brilliant 

 faces and cleavages were visible. 



There were a few smaller crystals upon the mass which were 

 nearly free from chalcedony ; one of these was so symmetrical 

 that it was measured under the impression that it was ortho- 

 rhombic and possibly a highly modified krennerite. The 

 angles, however, quickly proved its identity with sylvanite. 



The dimensions of the crystal were approximately 1 X 1 X 2 mm 

 in the directions d, b, c. For better adjustment the crystal 

 was mounted in the two-circle goniometer with the large 

 b == (010) face parallel to the vertical circle, and centered by 

 this face and the faces of the zone [100 001]. The results 

 were then transformed. 



Twenty-six forms were identified, of which twenty have been 



previously described by Dr. Chas. Palache* on crystals from 



Cripple Creek; two others, J^=101 and J9 = 112, are recorded 



forms not previously noticed on the crystals from this locality 



* This Journal, x, 419, 1900. 



