232 



University of California Publications. [Geology 



The new form (102) occurs on several of the crystals in small 

 triangular faces. Headings were also obtained for other prisms, 

 but owing to the striated condition of the prismatic zone they 

 were not definitely established as forms. 



IV. — Enargite from Alpine County. 



Crystals of enargite from the Morning Star mine were orig- 

 inally described by Silliman, 1 but he gave only the unit prism 

 and the three pinacoids as present. In looking over some speci- 

 mens of pyrite containing crystals of enargite from this mine it 

 was seen that more forms existed than those given by him. The 

 crystals are prismatic in habit and terminated on one end by a 

 broad basal plane and attached to the matrix at the other. The 

 habit and combination are seen in plate 20, fig. 9. 



The forms observed were : 



c 



(001) 





/' ( 



250) new 



1c (101) 





a 



(100) 





/ (130) 







b 



(010) 













m 



(110) 



















Me 



asured 



Calculated 













P 



<t> 



P 



c 



001 



0' 



00' 



0°00' 



0°00' 



0°00' 



a 



100 



90 



00 



90 05 



90 00 



90 00 



b 



010 







00 



90 05 



00 



90 00 



m 



110 



48 



40 



90 05 



48 56 



90 00 



f 



250 



24 



43 



90 05 



24 40 



90 00 



1 



130 



20 



42 



90 05 



20 56 



90 00 



k 



101 



90 



00 



44 00 



43 20 



90 00 



The dome k (101) was very small and only an approximate 

 reading could be obtained, but it was sufficient to establish the 

 presence of the form. 



The new prism f (250) was present on one crystal as a nar- 

 row face and the reading was good. A pyramid was also present 

 but the face was dull and its symbol could not be definitely de- 

 termined. 



V. — Arcanite prom Orange County. 



A few small yellowish plates of a mineral which were sent to 

 the writer by Mr. Norman E. Smith for identification proved 

 to be the natural potassium sulphate. They came from Tunnel 



i American Journal of Science, 1873 (3), 5, 384. 



