276 THE PENOKEE IROlSr-BEARING SERIES. 



fractured chert and iron ore, known to the miners as mixed ore, is found. 

 In passing n\) still further, this mixed ore grades into the ordinary ferrugi- 

 nous chert of the lower horizon of the iron formation. 



To sununarize, then, the boundaries of the ore deposits are to the south 

 either fragmcntal quai'fzite or ferruginous quartz rocks in the ore forma- 

 tion, generalh- tlie foniur; under tlie ore, the dike rocks; and, ahove the 

 ore, the ty})ical ferruginous cherts of the district. 



rractical (Ictlnctioiis to hi' appUed hi, protipccfnni and iiiii/iiHf. — The first 

 essential in wise prospecting in the Penokee district is to tind the junction 

 of the ore formation and the underlying fragmental tpiartzite.' Having 

 determined the position of the foot-wall (juartzite at several places, the 

 next step should be to run a line of test pits east and west just north of the 

 line between the ore formation and (piartzite across the property to be 

 exjdorecl. ( )ther conditions being equally favorable, the west end of 

 the proJlcrt^• slioidd lie tirst examined, for tlic l)odies of ore almost 

 always pitch to tlic cast, and a deposit foiuid upon tliis i)art of the property 

 will be likely to n'lnain longer on the land to l)e explored. If the above 

 pre2)aratory work (hn's not develop an ore l)od}', but a dike rock is struck, 

 the thickness of this dike, its inclination both to the south and to the east 

 or west should l)e carefully determined. If its dip cannot be made out, 

 assume that it is to the east of south. If, then, the dike is actually found 

 to have or is taken to have an eastern jiitcli, very careful exploration 

 should l)e made in ihe triangular area ])etween the foot-wall (piartzite and 

 this dike to a distance of 2(MI or ;50() feet east of tlie junction of the dike 

 and (luartzite and an increasing distance nortli in passing to the east. For 

 if an ore b(Kl\' exists witliin a reasonal)le distance from the surface upon the 

 i)roperty in (piestion, this is tlie place, as shown by tlie ;ictual position of 

 pl•e^■i(m.sly worked deposits, at which it is most likely to be found. 



The kuown existence of a dike just west of a property to be explored 

 would be a second good reason for a tliorough exploration upon the 

 west side of the propert\-, based upon the chances of tindiug an ore 

 deposit whicl: icsts upon this dike and the (piartzite, which, because of the 



'Till' (lilVi rciicrs between these two ihi.s.scs ol' idiUs liave lieeii given in detail, chapters ivand v. 

 Tliey are -so unlike ll];it :i |iraii i(:il mail w liii lias ixaiiiiiieil llie iliert ill wliieh tlie (ire oeenrs and the 

 loot-wall ijiiartzite at a lew Unalilies can reailil.v distinguish Ijetweeu them at sight, 



