ART. 9. MINERALOGIC NOTES ON PUCHERITE, ETC.—SHANNON, 9 
superior measurements, it is necessary to take the mean value for po, 
namely 0.7327. With this value assumed, the forms s(111) and 
m(110) yield for g, the values 0.4161 and 0.4112, respectively. Again, 
it is necessary to adopt the average of two values, and the axial values 
obtained for the crystal are as follows: 
Po =0. 7327 a=0. 5645 
Jo= - 4136 e—. 41366 
The above value for the a axis is practically identical with that of 
Wherry for the Pennsylvania material (a=0.5640), while the ¢ axis 
is somewhat greater than Wherry’s (c=0.4040). The present exam- 
ination merely adds another observation to the four or five already 
available. 
In habit the crystals of the Arkansas specimen are not unusual, as 
shown in Figure 9, the forms being 6(010), m(110), p(101), and s(111), 
all prominently developed. There is a tendency for the crystals to 
aggregate in almost parallel position or in sheaves. The prismatic 
faces are slightly striated vertically. The angles measured on the 
only really satisfactory crystal examined are below compared with 
the angles calculated from the above derived values for the axes: 
Calculated and measured angles of wavellite. 
| Measured. | Calculated. 
Letter. | Miller. | Symbol. 
| ge p ) p 
°o 4 fe} 7 ° ds fe} 4 
b (010) oo 0) 0 06 90 00 0 00 90 00 
b (010) oo 0) 0 06 90 00 0 00 90 60 
m (110) co 60 47 | 90 00 | 60 33 | 90 00 
m (110) foo) 60 46 90 060 60 33 90 00 
m (110) co 61 04 90 00 60 33 90 00 
m (110) © 60 583 | 90 00 | 60 33 | 90 00 
Bute. COL) 10 SOLS eal SEue 10a 290 00). ke sGie 14 
D (101) 10 90.03) |.36 10| 90 00 1 36. 14 
s (111) i 60 26 | 40 06 | 60 33 | 40 05 
s (111) 1 60 15 | 40 18 | 60 33 | 40 05 
Ss (111) 1 60 33 40 14 60 33 40 05 
$ (111) 1 60 40 | 40 01 | 60 383 | 40 05 
In an endeayor to obtain further crystallographic data on the 
Arkansas wavellite a number of specimens of this material were ex- 
amined. The best specimen from this locality in the Museum col- 
lections (Cat. 45866) consists of spherulitic aggregates of divergent 
crystals, which are transparent and of a beautiful sea-green color. 
Although in the body of the spherical group the crystals are deformed 
