PETROGRAPHIC GEOLOGY AND DESCRIPTIONS. 361 



Quartz-porphyry. Hematite. Jaspilyte.] 



* * * These jaspery pieces, generally smaller than a butternut, but sometimes as large as one's fist, are nearly 

 always angular, or but little rounded, and are in some portions thickly sprinkled over the surface of the schists." 

 Ref. Annual Report, ix, pages 102, 103. (The section described as No. 427, in Bulletin ii, page 113, is not 

 of this rock.) 



Meg. The hand samples show two red-banded jaspilyte pieces in a rock which 

 is somewhat similar to No. 426, but is more decayed and roughly schistose. A few 

 small feldspars and quartzes are present in this rock. 



No section. 



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



No. 428. QUARTZ-PORPHYRY. ( Altered. ) 



Rison's place, Ely island, Vermilion lake. 



Ref. Annual Report, ix, page 103; Annual Report, xviii, page 20; Annual Report, xix, pages 125, 127. 



Meg. Specimen missing. 



Mic. The section is too thick for careful study. It shows numerous highly 

 altered feldspar crystals and a few small quartz grains in a groundmass which is 

 composed largely of sericite with also probably quartz and feldspar. Pyrite and con- 

 siderable siderite are present; also some specks of an opaque gray substance, and one 

 piece of Muscovite which contains some of this opaque substance. Other similar areas 

 are also seen, but they are much decayed. One section. 



Age. Archean (Keewatin). 



Remark. See chemical analysis under No. 395. u. s. G. 



No. 429. HEMATITE. 



North ridge, near Tower; probably in N. V z sec. 27, T. 62-15 W. 



Ref. Annual Report, ix, pages 103, 104. Compare No. 871, which is hematite from the Lee mine on the 

 South ridge. 



Mey. The specimens show the usual, hard, glistening, crystallized hematite of 

 the Vermilion iron range at Tower. A little quartz is present, and there are small 

 cavities into which project minute plates of hematite. In some of these cavities is a 

 little limonite. 



Mic. The section shows hematite and coarsely crystallized quartz. The hematite 

 sends small fibres into the quartz where the two minerals are in contact; and in 

 places there is a narrow band of these fibres a little removed from, but parallel to, the 

 outline of the hematite. The quartz is much clouded, this feature being in part due 

 to minute dark specks, most probably of hematite, and cavities filled with liquid, 

 frequently also containing bubbles. 



One section. 



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



No. 430. JASPILYTE. 



Same locality as No. 429. 



Ref. Annual Report, ix, pages 103, 104. Compare No. 866, which is jaspilyte from the South ridge. 



