THE MINERALS OF IDAHO 



Measurements of aragonite, Figure 49 



239 



Quality, description 



Medium _ 

 ....do.... 

 Excellent, 

 Very poor 

 ....do.... 

 Excellent. 

 Very poor 



Measured 



58 51 



00 



17 



90 00 



60 41 



20 30 



84 29 



86 37 



88 06 



53 37 



33 00 



36 00 



61 34 



62 00 



Calculated 



58 06 



00 



00 



90 00 



58 06 



17 49 



81 09 



85 48 



86 41 

 55 14 

 30 04 

 34 17 

 62 09 

 57 22 



Crystal 50 is similar but stouter and, as shown in the drawing, has 

 a peculiar reentrant angle at the summit. It shows the same forms 

 plus a single face approximating the indices (545). This crystal 

 gave the following angles: 



Measurements of aragonite, Figure 50 



Crystal 3, shown in figure 51 is similar to crystal 1, but without' 

 (Z(102) and with one face of 5(332). This crystal gave the following 

 measurements : 



Measurements of aragonite, Figure 51 



In addition to the peculiarly unsymmctrical development there 

 will be noted in the angle tables a marked and rather constant devia- 

 tion of the measured from the theoretical angles. This may in part 

 be due to the difficulty of orienting crystals of this habit for measure- 

 ment on the goniometer and to the imperfect character of the crys- 

 tals, but the consistent lack of agreement suggests rather a mineral 



