W. T. Schaller — The Alunite-Beudantite Group. 359 



Art. XXXIX. — The Aluniie-Beudantite Group; by 

 Waldemar T. Schaller. 



Introduction. 



The analysis of the new mineral hinsdalite, described in an 

 earlier paper (this Journal, October, 1911), led me to review 

 carefully the various minerals forming the alunite-beudantite 

 group. This review has brought out several points in regard 

 to the relationships of some of these minerals, about which it is 

 very desirable to obtain more definite and accurate information. 

 Some of the suggestions offered in this paper must remain 

 unsettled until such new work can be performed. Prior* has 

 brought together the various minerals belonging to this group 

 and clearly shown their similarity in composition and in crystal 

 form. Before this comparison is again repeated here, some 

 short discussion bearing on members or possible members of 

 this group will be given. 



The probable identity of hamlinite with goyazite. 



Goyazite was described by Damourf in 1884 as a hydrous 

 phosphate of alumina and lime, the rather improbable formula 

 being given as 3Ca0.5Al 2 3 .P 2 6 .9H 2 0. Hussak^; has recently 

 tested the original specimen of Damour and found that stron- 

 tium was present in greater amount than lime, so that goyazite 

 is, in reality, a hydrous phosphate of alumina and strontia. 

 Hartley, in analyzing plumbogumniite,§ has suggested that the 

 accuracy of Damour's separation of P 2 6 from A1 2 3 was open 

 to serious question, due to the method used. If we assume 

 that a similar inaccuracy is true for his analysis of goyazite, 

 then an interesting conclusion becomes at once evident, namely, 

 that the mineral described and analyzed by Penfield and named 

 hamlinite is identical with goyazite. The probable identity of 

 goyazite and hamlinite can be best shown by a comparison of 

 their properties. 



The hamlinite from Maine contains a little barium and fluor- 

 ine, but their amount, in comparison to that of strontium and 

 water (hydroxyl) respectively, is small and moreover the 

 absence of barium and fluorine in goyazite has not been 

 established. 



* Prior, G. T., Note on a connection, between the molecular volume and 

 chemical composition of some crystallographically similar minerals. Min- 

 eral. Mag., vol. xiii. p. 217, 1903. 



f Bull. soc. rain, franc, vol. vii, p. 214, 1884. 



% Hussak, E., Uber die sogenannten " Phosphat-Favas '' der diamantfu.hr- 

 enden Sande Brasiliens. Min. petrog. Mitt., vol. xxv, p. 335, 1906. 



§ Hartley, E. G. J. , On the constitution of the natural arsenates and 

 phosphates. Mineral. Mag., vol. xii, pp. 223, 225, 1900. 



