412 THE PENOKEE lEON-BEAKING SERIES. 



made by Becke. In many of the sections a new amphibole has attached 

 itself to secondary liornblende.^ There are here, then, two hornblendes, 

 one of whicli is parainorphic, while the otlier has grown after the rocks 

 reached a solid state. The added amphibole has found room for itself, as 

 in the case described by Becke, by penetrating the suiTOunding feldspars. 

 The new amphibole is also found, as has been noted, included in the partly 

 decomposed feldspar in numerous small independent individuals. This 

 new amphibole is fibrous, of a pale green color, is not strongly pleochroic, 

 and often shows distinctly its intersecting prismatic cleavage. It has all 

 the characteristics of the variety described as smaragdite. The crystallo- 

 graphic continuity of the paramorphic and new amphibole when the two 

 are contiguous is as jjlain as in the case described and figured Ijy Becke, 

 where, however, the hornblende cores seem to have been original. 



Fio. 10.— Horublende enlargement uf :iugite in ili.ib.ise. 



In other diabases from the same locality the greater part of the augite is 

 unaltered. In these cases nearly every individual of this mineral is surrounded 

 by a sheath of smaragdite. Tliis smaragdite has clearly formed subsequently 

 to the consolidation of the rock, as is shown by the following facts: It cuts 

 into the surrounding feldspar in the most in-egular manner. The augite 

 cores have the forms common in many diabases, being bounded by well 



I R. D. Irving and C. R. Van Hise: Geol. of Wis., 1882, vol. IV, p. 663. R. D. Irving: On the 

 Paramorjihic Origin of tlie Hornblende of the Oystalliiie Rocks of tlie Northwestern States; Am. 

 .Jour. Sei., M series, :88."), vol. xxvi, p. 27. R. D. Irving: Supplement to paper on the Paraniorphic 

 Origin of the Hornblende of the Cr.yst.alliue Rocks of the Nortli western States; Am. .lour. Sei., .'{d 

 Berios, 1884, vol. xxvil, p. l.SO. M. E. Wad8W(n-th : Notes upon the (ieology of the Inm and Copjier 

 Districts ofLake Sni)erior, 1880. G. H. Williams: On the Paramorphosis of Pyroxene to Hornlileude 

 in l{ocks; Am. .lour. Sei., 3d series, 1884, vol. xxvill, p. 259. U. H Williams: Bull. U. S. Oeol. Sur- 

 vey, Nos. 28 and 02. 



