PETEOGEAPHY— QUAETZITES. 473 



The quartzite from Rapid Creek [73] is gray in color and very uni- 

 form and compact in structure. Under the microscope, the quartz is 

 crystalline and pure, containing microlites which have the sharp edges of 

 crystals, and also small greenish leaves of mica arranged in parallel rows 

 and pointing in one direction. This structure gives a little schistose charac- 

 ter to the rock. Magnetite, as usual, is present in sharp angular grains, and 

 also some mica. 



No. [75], from the same locality, is more pinkish in color, and in the 

 section shows crystalline quartz with cavities and microlites, the latter 

 being faintly dichroitic. There is much more mica than in [73], which 

 fact brings it nearer to mica-schist in character. 



Jasper [92], from Jasper Hill, Box Elder Creek, is of a red color, witli 

 veins of white quartz through it. Under the microscope, the quartz is seen to 

 be very fine granular, with a reddish-brown pulverulent pigment, which is 

 no doubt oxide of iron. There are also some opaque, dark, cubical and 

 triangular crystals with hollow centers, the remains of decomposed pyrite. 



In the quartzite from Box Elder Creek [200], which is from light-gray 

 to flesh color, the quartz grains are somewhat rounded, and in the interstices, 

 often surrounding the quartz particles, is seen a cementing material which 

 has the appearance of having flowed in streams through the crevices when 

 in solution, so as to fill up all to a solid mass. This allies the rock 

 more to the sandstones than to crystalline quartzites like the former ones. 

 There is some mica and a little orthoclase present, and in the quartz are 

 cavities and long, exceedingly slender microlites, similar to those in speci- 

 men [169]. 



The color, structure, and appearance under the microscope of [201], 

 also from Box Elder Creek, are the same as the above, except that there is 

 less mica. 



The quartzite, however, from Amphibious Creek [204] is crystalline, 

 the quartz being sharp and angular in outline, and full of very large cavi- 

 ties and microlites There are also masses of fibrous, dichroitic horn- 

 blende in great abundance, and some mica. The mineral observed as horn- 

 blende does not show any lines of cleavage, but it has not the appearance 

 of mica, and in the weathered parts of the rock these masses have become 



