384 THE PENOKEE IRON BEARING SERIES. • 



8. Greenstonecoiijjloinerate uortli, of 7. SpeL'iiuen Ito^l (slide 2977), 1040 N., 

 1500 W., Sef. 14, T. 47 N., R. 44 W., Michigan. 



The iiiatiix of the coiigiomerate i.s dark mottled green, line grained, and sehis- 

 to.se. It i.s .studded with pebbles and bowlders, some of the latter being of large size 



The thin j^ection is eut from the matrix. A continnou.s ramifying mass of non- 

 polarizing green chlorite and cherty and clialcedonic quartz contains uuinerou.s 

 rouiulish c((mple.\ areas of epidote, many small areas of titanite, few mucli altered 

 crystals of feldspar, and occasionally large areas of calcite, these latter apparently 

 replacing feldspars. There is nowhere any evidence-of fragmental material. Parts 

 of the section are quite like au altered eruptive, and it thus appear.s probable that the 

 matrix, as well as the fragment.s of this rock, is almost wholly or wholly a volcanic 

 product. 



Section along and near the ea^t line of Sees. 14, 23, and 26, T. 47 If., R. 44 JV., Michigan. 



9. Greenstone-conglomerates. Specimens 9358 (slide 3029), 400 N., 1525 W. ; 

 9357 (slide 4932), 450 N., 1700 W., Sec. 25, T. 47 N., E. 44 W., Michigan. 



The rocks are in nowise difterent from 6, except that they show a more decided 

 schistose structure. 



The thin sections show no difference between matrix and pebbles. The back- 

 ground appears to c(msist of amorphous gray material, in which are included exceed- 

 ingly Hnely crystallim^ cidorite, quartz, epidote, perhaps a little actiiiolite, and here 

 and there much altered porphyritic crystals of feldspar. A few large roundish areas 

 of quartz or calcite, or both, of an amygdaloidal character arc seen. So far as the 

 sections go, one would call this rock a schistose greenstone, and yet the conglomeratic 

 appeaiance of the exposure is marked. 



10. Chlorite-slate, nortli of 9. Specimen 10413 (slide 4018), 800 N., 1625 W., Sec. 

 25, T. 47 N., K. 44 W., Michigan. 



The rock is dark green to black, aphanitic, very finely lanjinated, and readily 

 cleaval)l('. 



Iti tliiii section an exceedingly rtnely crystalline (piartzose background contains 

 abundant chlorite and small particles of black an<l dark brown ferrite. The arrange- 

 ment of the chlorite and iron otide corresponds with the lamiuie of the rock. Con- 

 tained ill tlie tine grained material are some larger grains of (juartz which are plainly 

 fragmental. 



11. Gieenstone conglomerate, north of 10. Specimen 74r)9 (slides 2050 and 

 2051), .US N., \V., vSec. 23, T.47 K, R.44 W., Michigan. 



The thin sections of this rock ilo not differ essentially from those of 6. 



12. Greenstone conglomerate; north of 11. Si)ecinien !»312 (slides 2970 and 

 2971), 9313 (slide 4929), 190 N., 20 W., Sec. 14, T. 47 N., R. 44 W., Michigan. 



