NO. 1867. CRYSTALLIZED VARISCITE FROM VTAH.—SCHALLER. 425 



miiiute crystals with the forms 6 (010), a (100), m (110), and c (001). 

 Of these, l, m, and c were well developed. The angle mAm'" 

 (110: ITO) is given as 65° 54', but it has not been possible to correlate 

 this angle with any simple form for the variscite-scorodite group. 



The following table gives the coordinate angles for the forms of 

 variscite. The table is adapted for measuring the cr3^stals by the 

 two-circle method, but, of course, it also gives the necessary inter- 

 facial angles. 



Variscite. 



The three possible orientations for the variscite crystals will now 

 be given and their relation to the orientation of the analogous min- 

 erals scorodite, strengite, and phosphosiderite studied. 



FIRST ORIENTATION. 



The fu'st orientation is the one chosen for the mineral, as it best 

 shows the relation of variscite to the other minerals and at the same 

 time yields the simplest indices for the crystal forms of variscite. In 

 the comparisons, two orientations are given for phosphosiderite, both 

 of which are different from the accepted position of that mineral. 

 The first, phosphosiderite (1), is the one suggested by Bruhns and 

 Busz^ and the second, phosphosiderite (2), is obtained by inter- 

 changing the a and c axes in the generally adopted position and then 

 doubling the new a axis. 



The close relation between the angles of variscite and the other 

 minerals of analogous composition can be seen in the table below: 



Comparison of angles (first orientation) . 



A comparison of the axial ratio also shows clearly the similarity 

 in values and at the same time shows the very close agreement of 



» Zeit. Kryst. Min., vol. 17, 1890, p. 555. Also given in Dana's System of Mineralogy, 6th ed., 1892, p. 823. 



