CRYSTALLOGRAPHIC NOTES ON WAVELLITE FROM BOLIVIA, 

 PENNSYLVANIA, ARKANSAS, AND BOHEMIA. 



By Samuel G. Gordon. 

 Wavellite usually occurs as hemispherical or globular aggregates 

 with a radiated crystalline structure, or very rarely as druses 

 of minute crystals. The crystallographic data on the mineral are 

 rather unsatisfactory due to the small size of the crystals heretofore 

 found and their imperfect character. On the 1921 Vaux- Academy 

 Expedition to the Andes, the writer obtained large slabs of beautiful 

 prismatic crystals measuring up to 2 X 3 X 6 mm. This material 

 forms the basis of this investigation. A study was also made of 

 the other specimens of wavellite in the collections, with the meas- 

 urement of crystals from Pennsylvania, Arkansas, and Bohemia. 



Crystals of wavellite were first measured by Senff 1 from Frank- 

 enberg, Saxony. These showed the following forms: b (010), 

 m (110), n (340), q (13.1.0), p (101), s (111), and o (121). 



Des Cloizeaux 2 noted the following forms on wavellite from 

 Montebras, France: b (010), m (110), n (340), s (111), and the 

 doubtful form r (5.11.6). 



Cesaro 3 described wavellite from Arbrefontaine, Belgium, with 

 the forms b (010), a (100), m (110), s (111), o (121), and p (101). 

 He suggested that the doubtful form r (5.11.6) of Des Cloizeaux 

 was probably o (121). 



Further examination of a crystal from Montebras by Ungemach 4 

 gave in addition the forms h (310), and 1 (430). 



Ungemach also measured good crystals from Moore's Mill, 

 Cumberland County, Pennsylvania, 5 which showed the combination 

 b (010), a (100), m (110), 1 (430), i (320), h (320), o (121), and s(lll). 



Finally, Wherry 6 listed the following forms on crystals from 

 Hellertown, Lehigh County, Pennsylvania: b (010), a (100), 

 1 (430), m (110), n (340), p (101), s (111), and o (121). 



The axial ratios obtained by these writers are listed in Table I. 

 A new value determined on crystals from Bolivia is given in Table II. 



l J. Senff; Pogg. Annalen, 18, 474, 1830. 

 2 A. Des Cloizeaux; Manuel de Mineralogie, II, 455, 1874. 

 3 G. Cesaro; Mem. Acad. Roy. Belgique, 53, 28, 1896. 

 4 H. Ungemach; Bull. Soc. Franc. Min. 35, 536, 1912. 

 6 Erroneously given as Cly, York County, Penna., which was the site of the 

 factory to which the mineral was shipped. 



6 Edgar T. Wherry; Proc. U. S. Nat. Mus. 54, 379, 1918. 



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