442 THE MARQUETTE lllOX-BEARIISfG DISTRICT. 



jasper. If coarse ij-rains were originally present they have been gran- 

 ulated by the mashing. Toward the southeast end of the area, near the 

 Kloman and Republic mines, the mashing was not so severe, and here two 

 classes of quartz are discriminated. Although no grains show cores and 

 enlargements, in some cases the coarser grains are cemented by a fine 

 mosaic, as in ordinary quartzites; in others the coarse and fine grains are 

 in alternate layers; while in a third case they are indiscriminately juingled. 



Where the Goodrich quartzite rests upon the Archeau, the basal rock 

 is entirely different from the above, being in two places a conglomerate 

 composed chiefly of material derived from the Basement Complex The 

 pebbles of the conglomerate were simple and complex fragments of quartz, 

 large grains of feldspar, and granitic pebbles composed of both. These 

 have been so intensely mashed that they are usually in elongated oval or 

 ribbon-like areas. Much of the coarsely crystalline quartz is granulated, 

 so that the quailzose pebbles consist of finely granular intei-locking quartz- 

 The feldspar fragments are usually much shattered. Along- the cracks 

 quartz and muscovite have largely developed. In one case the stresses have 

 jDroduced an unusually strongly marked fissility in two directions, which in 

 section resembles the double cleavage of calcite. Where the decomposition 

 went far enough the areas once occupied by feldspar consist of interlock- 

 ing crvstalline masses of quartz, muscovite, and residual feldspar. In the 

 pebbles which consisted of quartz and feldspar together the effects uj^on 

 the latter mineral were the same as in the pebbles which consisted of feld- 

 spar alone. The matrix of the conglomerate is a muscovitic aud feldspathic 

 quartz-schist. The feldspar comprises both orthoclase and plagioclase, the 

 latter including much microcline. In some of the sections this feldspar is 

 so abundant as to be a principal constituent. In a number of slides the 

 matrix is completely crystalline, thus becoming mica-schist or mica-gneiss. 

 If it were not for the conglomeratic character of these rocks their sedimen- 

 tary origin could not be asserted from evidence shown by the thin section. 

 As accessories ui the conglomeratic schist aud gneiss, magnetite, biotite, 

 chlorite, and epidote are found. 



By a lessening of the amount of magnetite the recomposed ore-bearing 

 rocks at the mines pass up into muscovitic quartz-schists. Also by the 



