192 



THE PENOKEE IRON BEAEING SERIES. 



side (if the outlt't of (jruiifliut lake, situated on the national boundary 

 between Minnesota and Canada. No. VIII (specimen 10598), by Mr, 

 Cliatard, is fidin the same beds, but fi-om an exposure on the northern side of 

 Gunflint lake. No. IX (specimen 10588), also by Mr. Chatard, is a fei-rif- 

 erous carbonate from another part of the north side of Gunflint lake. No. 

 X (specimen 10157), by Mr. Riggs, is a black slaty and carbonaceous iron 

 carbonate, exposed at Kakal)ikka falls on the Kaministirpiia river, Canada. 

 And No. XI (specimen 10160), also by Mr. Kiggs, is from a less carbona- 

 ceous phase, exposed at the same place as No. X. The rocks repi-esented by 

 Nos. VII and XI, inclusive, of these analyses are all from the so-called 

 Animikie series of northeastern Minnesota and the adjoining portions of 

 Canada. 



AnaUjSi'S of iroit-lHiirini/ rtirbouah-s. 



* UiKU'teniiiiied. 



The rocks of the second type, which we have collected under the gen- 

 eral designation o( fi'iriijiiiioiis slates and fcni(i/iit<>iis cherts, have in common 

 a ])rominent siliceous constituent, which is always of a ncmfragmental nature, 

 and ranges in crystnlliziition from a wholl}' though minutely crystalline con- 

 dition, tlirough parth' crvstalline and chalcedonic jihases to an entirely amor- 

 rihous ])hase, the se\cral jihases being frecpU'iitly associated in the same thill 



