242 



BULLETIN 131, UNITED STATES NATIONAL MUSEUM 



A specimen labeled as from the croppings of the Golden Glow- 

 mine, Warm Springs district, consists of minute simple colorless 

 cerusite crystals having the habit shown in the drawing, Figure 52, 

 on spongy limonite. The measurements obtained on crystals from 

 this specimen are given in the following table: 



Measurements of cerusite (fig. 52) from Golden Glow mine 



A second specimen labeled as from Blaine County, but without 

 more detailed locality, was probably from the Independence mine. 

 It contained small cerusite crystals in cavities in galena. These were 

 prisms elongated in the vertical direction and all twinned on the unit 

 prism ra(110), some of them greatly resembling quartz crystals as 

 shown in Figure 54. The twinning is clearly shown in the crystals 

 of the type shown in Figure 53, one of which was measured. This 

 measured crystal gave the angles of the following table, each of the 

 three crystals making up the twin being considered separately, the 

 orientations being as shown in the drawing, Figure 53. The angles 

 are for the normal position used for cerusite. 



Measurements of twinned cerusite from Blaine County, Figure 53. 



Form 



No. Letter 



7712- 

 62.. 



Pi- 



Symbol 



Gdt. Miller 



00O 



Ooo 



1 



Oco 

 1 



Ooo 



1 



100 

 110 

 010 



111 



110 

 010 



111 



110 

 010 



111 



Quality, description 



Very poor 



do... 



Good 



Very good 

 Medium. 



Fair 



Very poor 



Good 



do... 



Poor 



Excellent. 



Measured 



90 26 



61 10 



18 

 58 40 

 60 44 



1 32 

 60 12 



7 26 



58 36 



11 



58 30 



90 00 



90 00 



90 00 



54 28 



90 00 



90 00 



54 47 



90 00 



90 00 



90 00 



54 06 



Calculated 



90 00 



58 37 



00 



58 37 



58 37 



00 



58 37 



58 37 

 00 

 58 37 



90 00 



90 00 



90 00 



54 14 



90 00 



90 00 



54 14 



90 00 

 90 00 

 54 14 



The three individuals of the twin bear the following angular rela- 

 tions to each other. 



v ( = v of crystal 1) A (vi) ( = v of crystal 2) = 120 34 

 (vi) (v of crystal 2) A (v 2 )o( = v of crystal 3) = 122 14 

 (v 2 )o(= v of crystal 3) A (v ) (=v of crystal 1) = 117 12 



