154 THE PENOKKE IHON-BEARING SERIES. 



.somewluit plentiful, (if a distinct greemsli tinge. The entire, or nearly 

 entire, absence of particles df any other mineral than (piartz in these 

 rocks is taken to indicate a yreater anioiuit of sortin<>- tlian has been 

 receiveil by materials which have composed the other ])hases of this forma- 

 tion. This conclusion is l)orne out bv the generally uniform size of the 

 (piartz fragments of the vitreous (piartzites, the sorting having been 

 carried s<t far as to remin e not only the particles of other minerals, but the 

 smaller particles of quartz. 



Microscopical cluiracfcr of (he simdsione, novaculite, and argillaceous 

 .slates. — (Phases 5, 6, and 7.) These phases of the' Quartz-slate member, 

 because of their relatively small importance, may be more rapidly 

 dismissed. The sandstone ])hase (PI. xix. Fig. 3) is an unusual one, having 

 been so far observed only In three localities, viz: In the vicinity of the 

 Ashland mine. Sec. 27, T. 47 N., R. 47 W., Michigan; in the vicinitv of the 

 Aurora mine. Sec. 23, T. 47 N., R. 47 W., ]\Iichigan, and at a point about 

 three-fourths of a mile east of Sunday lake. Sec. 10, T. 47 N., R. 45 W., Mich- 

 igan. In the first two localities it occurs at a high horizon immediately 

 beneath the overlying vitreous (piartzite; but in the last jjlace the sandstone 

 occurs on the contrai-v at a low horizon. Macroscopically these sandstones are 

 of a rather tine grained arenaceous textiu'e and from red to white in color, 

 these colors l)eing often very irregularly blotched. An examination of the 

 hand specimens, without reference to their source, would certainlv suggest 

 that they came from some modern sandstone formation rather than from 

 so ancient a terrane as that we are now concerned with. A[icroscoj)ical 

 examinations show, however, that they are merely less consolidated phases 

 of the (piartzites or feldspathic quartz-slates above described, these rocks 

 l)ein<>' in fact no whit less fraymeutal in texture than the sandstones them- 

 sehes. 



The novaculite or Avhetstone-like phase (PI. xviii. Fig. 4) of the Quartz- 

 slate member occurs here and th(M'e in thin seams in the eastern half of the 

 b(dt. (_)ne of the most noteworthv localities for this phase is the gorge of 

 '^rA'ler's fork where the novaculite shows on the west bank of the river at 

 aliout 200 paces north of the quarter post on the east line (»f Sec. 33,' T. 45 

 N., R. 1 W., Wisconsin. This uo\ aculite is nothing moi'e than a vei'V fine 

 and even grained variety of the feldspathic cpiartz-slates, aboA'e described. 



