220 PHYSIOGRAPHY. CLASS il. 



crystallised and massive varieties, in the alps of Savoy and 

 Dauphiny, in St Gothard in Switzerland, in the Tyrol, in 

 Salzburg, Carinthia, in the Pyrenees, in Norway and Swe- 

 den. It is found in considerable quantity near Glasgow in 

 Scotland, also at Reichenbach near Oberstein in the Pala- 

 tinate, in the Faroe islands, in America, &c. 



GENUS IV. DYSTOME-SPAR. 

 1. PRISMATIC DYSTOME-SPAR. 



Prismatic Datolite. JAM. Syst. Vol. I. p. 345. Man. p. 139. 

 Datholite. Boi ate of Lime. PHILL. p. 1 77. Datholith. 

 WERN. Hoffm. H. B. III. 1. S. 143. Datolith. 

 HAUSM. III.S.865. Datolith. LEONH. S. 588. Chaux 

 boratee siliceuse. HAUY. Tabl. comp. p. 17. Traitd, 

 2de Ed. T. I. p. 590. 



Humboldtite. LEVY. Ann. of Phil. Febr. 1823. p. 130. 

 Id. PHILL. p. 380. 



Fundamental form. Scalene four-sided pyramid. 



p= * , 133 47, 77 41 '- Inclina - 



, tion of the axis = 1 41' 30", in the plane of 

 the long diagonal. Vol. I. Fig. 41. LEVY.* 



* The angles of incidence and dimensions of the regular 

 forms of the present species are those given for Humboldtite 

 by Mr LEVY ; as calculated from the angles given for the sub- 

 stance, Pr = 115 45', P + ca = 77 30' and the inclination of 

 the axis = 1 41' 30". There can be no doubt, that the crys- 

 tals represented in Figs. C8. 69. and 70., from the collection of 

 the Johanneum at Gratz, are this same Humboldite, which Mr 

 MOHS recognised to be Datolite, from the comparison of the 

 rest of their characters, particularly hardness and specific gra- 

 vity. Also the varieties from Arendal frequently possess a 

 hemi-prismatic character, as is evident from Fig. 67. The po- 

 sition in which Mr LEVY compared the crystals of Datolite 

 with those of Humboldite is different from that adopted in 

 the present work. The want of symmetry in those of Datolite, 

 as referred to his Fig. 2., is contiguous to the opposite acute 

 lateral edges of m = 76 35', a prism which agrees in position 



