32 Van Hise — Iron Ores of the Penokee-Gogebic Series. 



Also 



_ i 



Herderite a : b : fc = 0-6206: 1 : 0-6352 



Beryllonite_.-#: b : c = 0-5724 : 1 : 0-5490 



The optical relations do not correspond very closely except 

 in the size of the axial angle, for which we have in herderite 

 2H a r = 72° 12' Dx. The refractive power of beryllonite is 

 a little lower than that of herderite (/3=l-6). It is certainly 

 most interesting that these two beryllium phosphates should 

 be found within a few miles of each other, and that the same 

 region should have yielded the rare beryllium silicate phena- 

 cite. 



In conclusion we would express our high appreciation of 

 the liberality of Mr. Sumner Andrews, of Lawrence, Mass., 

 his brother, Mr. Charles Gr. Andrews, and Mr. Lorin Merrill 

 who have placed in our hands all the best material for study of 

 this rare and beautiful mineral. Without this it would not 

 have been possible to have made our investigation with the 

 completeness that the interest of the subject has made it merit. 



Art. III. — The Iron Ores of the Penokee- Gogebic Series of 

 Michigan and Wisconsin; by C. E. Van Hise. With 

 Plate II. 



[Published by permission of the Director of the U. S. Geol. Survey.] 



The Penokee-Gogebic Series runs nearly continuously from 

 the vicinity of Numakagon Lake, T. 44 K, E. 6 W., Wis., to 

 Gogebic Lake, T. 47 JST., E. 42 W., Mich., a distance of more 

 than 80 miles. The west part of this belt was first fully 

 described by Professor E. D. Irving, and Mr. Charles E. 

 Wright.* A general account of the Eange has been given by 

 President Chambeiiin.f Other papers have also been pub- 

 lished in this Journal, which have from various standpoints 

 treated particular questions in reference to this region.;}: It 

 will, however, be necessary here to give very briefly its struct- 



* Geology of Wisconsin, vol. iii, 1880, Part III, pp. 100-167, The Huronian 

 System, by R. D. Irving; Part IV, pp. 239-301, The Huronian Series west of 

 Penokee Gap, by C. E. Wright. 



f Geology of Wisconsin, vol. i, 1883, pp. 80-94, The Huronian Age, by T. C. 

 Chamberlin. 



X This Journal, III, vol. xxix, pp. 237-245, Divisibility of the Archasan in the 

 Northwest, by R. D. Irving. Vol xxxi, pp. 453-459, Upon the Origin of the 

 mica-schists and black mica-slates of the Penokee-Gogebic iron-bearing series ; 

 by C. R. Van Hise. Vol. xxxii, pp. 263-265, Origin of the ferruginous schists and 

 iron ores of the Lake Superior region, by R. D. Irving ; Vol. xxxiv, pp. 257-259, 

 Is there a Huronian Group? by R. D. Irving. 



