INTERESTING LOCALITIES OF NEGAUNEE EOJIMATION. 389' 



Champion area. — Passiiig wesst tVoiii Mouiit Humboldt, We find no expo- 

 sures of the Negaimee formation tui- alxnit 3 nnles. Adjacent to and south- 

 east of Champion (AtLas Sheets XII and XIII) there aj^ain ap[)ear numerous 

 exposures of g-riinerite-magnetite-scliist, constituting- a high ridge running- 

 northwest and southeast. The rocks are very dense and refractor\-, retain- 

 ing- their gdacial forms ahnost perfectly. Tliey consist of altcrnjitc hands 

 which vary in the amount of contained quartz. The strongly g-riineritic 

 bands are ligjht-g-reen; those with little g-riinerite are dull-white. While 

 the rocks have a strike corresponding- in a g-eneral way with that of the 

 formation, they are influenced by the great masses of intrusive green- 

 stone. This is well shown by the exposures of g-rihierite-schist in the 

 SE. \. sec. 31, where the strike curves about the intrusive mass of green- 

 stone. West of this intrusive is another, of less magnitude, and ac-ain 

 the griinerite-schists have a strike parallel to it. North of the griineritic 

 rocks, constituting- the foot-wall of some of the mining- jjits, is ma<'-netitic 

 chert similar to that of the ^lichigamme mine. The quartz ])ands are 

 of the white variety; the ferruginous bands are largely crystallize<l mao-- 

 netite. In thin section the griineritic rocks of Champion are ver^• similar to 

 those of Mount Humboldt. They are, perhaps, somewhat coarser grained, 

 and quartz is rather more abundant. The slides of the magnetitic ja.spilite 

 are iu all respects similar to those of the foot-walls of the Michigamme 

 and Spurr mines. The quartz is rarely coarsely crystalline. Each giaiu 

 includes crystals of magnetite. Also the magnetite is iu nearly solid l)ands 

 between the siliceous layers. The crystals of magnetite at the borders of 

 the bands project into the quartz. The amphibole is all of the pleoclu-oic 

 variety, giving blue, green, and yellow colors. 



Republic area. — TliB remaining important exposures of the district are 

 those adjacent to the town of Republic (Atlas Sheet XI). These are 

 subsequently described in a separate chapter devoted to the Republic trough, 

 but it will here be remarked that the lower part of the Negaunee formation 

 is griinerite-raagnetite-schist, while the upper part is typical coarse jasper. 

 The lower part of the formation is much intruded by greenstones, which 

 seem to follow the bedding of the rock in a general way for short distances, 

 the same as at Humboldt, although the beds are also crossed. It is to be 

 noticed, however, that, as in previous cases where the greenstones appear,. 



