88 The Ottawa Naturalist. [August 



Hand specimen is a fine-grained greenish rock, impregnated 

 with pyrite and chalcopyrite. 



Under the microscope, the rock is seen to be much altered 

 and to present a distinct porphyritic character, the phenocrysts 

 being relatively more abundant than the groundmass, which is 

 composed mainly of felspar laths Of the phenocrysts, the felspar 

 is by far the most abundant, some having good idiomorphic forms, 

 while others show broken individuals. Augite is also abun- 

 dant in medium-sized grains, which, however, have undergone 

 considerable alteration, in some places being completely changed 

 to epidote and chlorite. Calcite is abundant as an alteration 

 product, and magnetite as an accessory constituent. 



The rock bears a distinct resemblance to No. 120, but is 

 relatively richer in felspar and may be considered to be a highly 

 altered basalt. 



No. 13. — Fine-grained dark igneous rock, with markedly por- 

 phyritic structure. From an exposure on Nevertouch 

 Creek, near its junction with Kettle River. 



Under the microscope, the rock is seen to consist of a rather 

 fine-grained groundmass, in which are imbedded well-defined 

 phenocrysts, which like the groundmass consist of plagioclase 

 and augite, Many of the smaller felspar grains are untwinned, 

 and all have undergone considerable alteration. Augite is quite 

 abundant in almost colourless grains, showing much alteration 

 to chlorite. It has a maximum extinction of 39*^, which, 

 with its other characteristics, determines it to be diopside. 

 A few crystals which, from their general appearance and 

 high double refraction, closely resemble olivine, are also 

 present. Some biotite occurs in the slides, but is very much 

 altered, now consisting largely of chlorite. A small amount of 

 epidote is present as an alteration product, and ilmenite, which 

 occurs associated with sphene, is abundant as an accessory con- 

 stituent. 



The rock is an augite andesite, or possibly, as suggested by 

 the structure, some dyke rock of similar composition. 

 No. 14. — From the Gorge at the mouth of Canyon Creek, where 

 it enters Nevertouch Creek. 



"The rock formation on either side of the gorge is of igneous 



