382 THE PENOKEE lEON-BEAEING SERIES. 



cemented by interlocking quartz and feldspar, the latter comprising both orthoclase 

 and plagioclase. The feldspar in this cementing material, unlike that contained in 

 the fragments, is usually fresh. This difference may be due to a more acid character. 

 Contained in one of the sections are quite numerous areas of a colorless mineral wliich 

 shows clea.vage in two directions, gives somewhat brilliant interference colors, and is 

 taken to be iiyroxeiie. Quite frequently roundish cores of this mineral luive a border 

 of fibrous material which terminates by a gradual fraying out. A few large frag- 

 ments of an undetermined mineral, which has very feeble double refraction, are seen. 

 (PI. XXXV, Figs. 3 and i.) 



Section in and near went half of Seen. 11 and ^'o, T. 47 N., R. 14 ir., Mivhif/an. 



3. Actinolite-chlorite-schists. Specimens !»377 (slide 3037), 1330 N., 25 W.; ri378 

 (slide 3038), 14135 N., 15 W., Sec. 22, T. 47 N., K. 44 W., Michigan. 



The rocks are dark lustrous green, fine grained, and finely laminated. 



The sections are mostly comjiosed of pale green nonpolarizing chlorite, needles 

 of actinolite and biotite, finely crystalline and chalcedonic quartz, and roundish 

 granules and clusters of granules of yellowish-gray titanite. lni)laccs the silica is so 

 abundant as to (constitute a matrix for the remaining minerals, while in other parts of 

 the sections the chlorite, biotite, and actinolite almost en'tirely exclude the quartz. 

 The actinolite is in needles, which intersect and often occur in radiating clusters. 

 Those included in the quartz are usually quite fresh, but those embedded in the chlo- 

 rite have altered to a large extent to biotite, all of which mineral is secondary to and 

 most often pseudomorphous after the actinolite. 



4. Ferruginous chlorite-slate, north of 3. Specimen 9341 (slide 3023), 1500 N., 

 1550 W., Sec. 23, T. 47 N., R. 44 W., Michigan. 



The rock is dark greenish-gray, aphanitic, and has a well developed slaty cleav- 

 age. 



The section is exceedingly fine grained. It consists of jiale green, fibrous, non- 

 jiolarizing chlorite, finely crystalline and amorphous silica, and of minute opaque or 

 nearly o]ia(iue particles of ferrite, with a little biotite. 



5. Calcific and chloritic slate interstratified with 4. Specimens 0342 (slide 2979), 

 9343 (slide 31 IG), 1500 N., 1550 W., Sec. 23, T. 47 N., R. 44 W., Michigan. 



The rocks are light grayish-green, fine grained and vary from slaty to schistose. 



Tlie thin sections consist of pale green nonjiolarizing chlorite and calcite or otluv 

 carbonate, and a finely crystalline chahiedonic and amorphous silica, with also apjKir- 

 ently some kaolin or sericite. Tiie carbonate is particularly abundant, and gives the 

 sections an api)carance closely allied to some of the sideritic cherts of the iron-bear- 

 ing belt. 



6. (Ireenstone conglomerates, interstratified with 4 and 5. Specimens 9338 

 (slide 3114), 9339 (slide 3115), 1500 N., 1550 W.; 7452 (slide 1906), 1500 N., 1710 



