90 



University of California Publications. 



[Geology 



continued crystallizations of rhombohedrons. The tubes are sev- 

 eral inches long', and their round surfaces show the outlines of 

 small rhombohedrons. They break always with the calcite cleav- 

 age. The stalactites have the customary shape and also show the 

 outlines of crystals, and their points are always terminated by a 

 clear crystal, consisting' of steep rhombohedrons 4R and -2R with 

 their edges modified by scalenohedrons. The faces of the scale- 

 nohedrons were too rounded for measurement. 



The stalactites in the cave are continually wet, water filling 

 their hollow centers and constantly dripping from them, so that 

 the growth is by successive crystallization instead of by the com- 

 mon evaporation and deposition of the carbonate. 



Occurrence. — Specimens of porous, yellowish brown earthy 

 limonite containing minute crystals of barite were collected by 

 F. M. Anderson from the Pine Hill mine, Nevada County. At- 

 tention has previously been called to this mine as containing gold 

 associated with barite. 13 



The crystals are perfectly colorless and exhibit two habits. 

 The crystals are slender prismatic, but in one habit they have 

 pointed ends while in the other the base is the only termination. 



Forms. — The forms present are : 



The front pinacoid is vertically striated and broader than the 

 prisms. The reflections from the unit prism and from the ter- 

 minal faces were exceedingly sharp. Most of the crystals have 

 pyramidal terminations and Fig 2 shows the general type. 



Measurements. — The measurements were made with the two- 

 circle goniometer, and the angles measured and calculated are as 

 follows : 



13 Amer. Jour. ScL, 1892 (4), 44, 57; 1894 (4), 47, 467. 



BARITE. 



V ) 320 | 



7T \o'd0\ 



X j 130 | 



c 5 ooi j 



d \102\ 

 o jOllj 

 z jlllj 

 / J H3 J 



