PETROGRAPHIC GEOLOGY AND DESCRIPTIONS. 663 



Tuff. Diabase. Green schist.] 



Age, Intrusion in the Upper Keewatin. 



Remark. The name of this rock was given by M. A. Michel Levy to the blue 

 porphyry of Esterel in 1897,* a laccolitic and intrusive rock of southern France pene- 

 trating Permian strata, which he shows is perfectly analogous to the laccoliths of 

 the Henry mountains. The chief chemical difference between this rock and that of 

 Esterel consists in the somewhat greater percentages of silica and of soda in this. 

 This high percentage of soda is in harmony with the aegirite nature of the pyroxene. 



N. H. w. 

 No. 1095. TUFF. (Porodyte?) 



Mallmann's peak, S. E. ^ sec. 30, T. 65-6 ; Kekequabic lake. 

 Ref. Annual Report, xv, pages 368, 397. 



M^eg. Banded graywacke and slate. 



Mic. The grains are angular, consisting of quartz and feldspar, embraced in an 

 abundant matrix of prevailingly green elements. There are also pebbles which were 

 probably originally glassy (zirM-i/fe), but now are dark constantly between the nicols 

 or are sprinkled sparsely with polarizing specks. This substance, in finer condition, also 

 constitutes much of the surrounding matrix. Some of these pebbles are black, with 

 fine dust of nuiijiu-tite. A little pyrite is scattered through the slide. One section. 



Age. Archean (Keewatin). N. H. w. 



No. 1096. DIABASE. 



From a dike making a couple of islands in Kekequabic lake, south of Mallmann's peak, N. E. % sec - 31. 

 T. 65 (i. 



Ref. Annual Report, xv, pages 368, 398 ; Annual Report, xxi, page 29. 



Dark, diabasic rock, of medium grain. 



Mir. An ordinary diabase, which, however, has been subjected to some dynamic 

 stress, as the pyroxenic element, which appears in the main to be still augite and is 

 ophitic toward the feldspars, is broken into several fragments (each crystal) which 

 cause a shifting extinction to pass over the crystal. The feldspars are all more or 

 less clouded by zoisite and by m'u-a. The rock has also some original crystals of 

 magnetite and some secondary adinolite and /n'iiniiit'. One section. 



Age. Dike cutting the Archean. N. H. w. 



No. 1097. GREEN SCHIST. 



S. E. }4 sec. :iO, T. 65-6 W. South shore of Kekequabic lake. 

 Ref. Annual Report, xv, pages 36S, :i'.)S. 



Mr;/. A rather soft, green schist, similar to many others in the vicinity. 

 Evidently consisting largely of hornblende. In the field this rock shows contorted 

 sedimentary structure. No section. 



Age. Archean (Keewatin). u. s. o. 



"Memoire sur !< porphyrc lilt-n clr 1'Kstrn ]. Hull. H< r. I'urli- Llml. fY/iiv ,V<>. r,7, tome ix. 1hf>r-lW, Paris. 



