320 



University of California. 



[Vol. 2. 











Measured. 



Calculated. 



a : 



P 



= (ioo) 



: (in) 



6l 40' 



61 40' 



a : 



e 



= (ioo) 



(IOI) 



57° 22' 



57° 22' 



a : 



m 



= <ioo) 



: (no) 



45° 0' 



45° 0' 



nr. 



P 



= (no) 



: (in) 



47° 5o' 



47° 5o' 



nr. 



X 



= (110) 



: (3ii) 



36° 41' 



36° 41' 



m: 



e 



= (no) 



:(I0I) 



63° 36' 



63° 35' 



P : 



X 



=(III) 



: (311) 



29° 57' 



29° 57' 



P ■ 



e 



=(III) 



(IOI) 



28° 20' 



28° 20' 



c : 



e - 



= (101): 



(on) 



44° 5o' 



44° 5o' 



x: 



P 



-(311) 



(no) 



53° 19' 



53° '9' 



x : 





=(311): 



(5n) 



n° 1 8' 



11° 22 r 



The crystals are remarkable for the large development of the 

 ditetragonal pyramid ,t'(3 1 1). It is present on all of the crystals, 

 with the faces nearly equal in size those of a(ioo) and ^(101), 

 these three forms predominating. The general habit and relative 

 size of the forms on the crystals are shown in Figure 5, PI. 9. 



A few of the crystals are water-worn, but the majority have 

 their edges very little roughened or their faces marred. The nearly 

 colorless ones are evidently bleached out, as very little heating of 

 the deep wine crystals produces perfectly clear colorless ones. 



The original source of the crystals is unknown to the writer, 

 but, judging from the very slight abrasion they have undergone, 

 they have not been transported a great distance. 



III. ESMERALDAITE, A NEW HYDROUS SESQUIOXIDE OF IRON FROM 

 ESMERALDA COUNTY, NEVADA. 



Specimens of yellowish-brown earthy material containing small 

 pod-shaped masses of a coal black mineral were sent to the depart- 

 ment, some years ago, by Mr. W. H. Shockley, from Esmeralda 

 County, Nevada, and analyses have lately been made of the material 

 by Mr. Schaller. 



The brown earthy mass is apparently a highly siliceous limonite 

 containing about 14% Fe 2 3 . The black mineral proves to be a 

 ferric oxide with a high percentage of water and with considerable 

 impurities, notably of phosphorus and aluminum. It has been 

 deposited in the cavities of the earthy mass in a solid amorphous 



