106 COLEMAN ON THE GEOGRAPHY 



Microscopic. — Nearly the whole of the rock proves to be made up of quartz in larger 

 or smaller fragments, sometimes looking as if clastic in origin. These are often sur- 

 rounded and wedged in by small, probably secondary, individuals as a tesselated border. 

 The larger grains have the usual inclusions, cavities containing water and also liquid 

 carbonic acid. In addition we find a few scales of muscovite, a fragment or two of horn- 

 blende, and some minute yellow grains, probably of titauite. 



Mica (Sericite) Schists. — Macroscopic. — These are lustrous, pearly or reddish grey 

 schists with wavy micaceous lamellœ folded about various minerals, such as garnet, stau- 

 rolite and disthene. All of these minerals sometimes occur in crystals an inch or more in 

 length, and they may be so crowded as to make up fully half the rock, garnet being 

 commonest and staurolite next in order. In such cases the rock should perhaps be 

 named garnet, staurolite or disthene schist. 



Microscopic. — Quartz occurs of the usual kind, but is variable in amount and at times 

 qirite absent. The chief constituent is sericite in wavy, confiisedly parallel scales ; but a 

 considerable amount of biotite is also found. The garnet is of a pale llesh-color in thin 

 sections. The staurolite displays a magnificent dichroism, orange red parallel to the 

 longest axis and yellow perpendicular to it. The less common disthene shows no pleo- 

 chroism, but has brilliant polarization colors. Small red brown grains and crystals of 

 titanite are very common. 



Gneiss. — Macroscopic. — A specimen obtained from a boulder, found near the trail on 

 the north east shore of the Columbia, appears to be gneiss, though none was seen in situ. 

 It is the only specimen of the kind known to the writer from the Canadian Rocky Moun- 

 tains. Could it have been transported, by glacial action, for instance, from the Selkirks 

 across the river? The rock is slightly schistose in appearance, mediu.m grained, and 

 light-brownish grey in color, with patches of black mica. 



Microscopic. — It contains little quartz, much microline and plagioclase and a quantity 

 of green, and also brown, biotite. Oxides of iron and epidote occur in small amounts as 

 decoiuposition products. 



(6.) French Creek {Big Bend Gold Region). 



Chlorite (?) Schist. — Macroscopic. — The only specimen at command was obtained at 

 Frenchtown four years ago. It is a finely-corrugated lustrous schist of a grey-green color 

 much darker than that of the sericite schist of SvTrprise Rapids on the other side of the 

 Selkirks. 



Microscopic. — It consists of quartz in small, clear portions, a very little plagioclase, 

 and much of a blue green mineral, probably chlorite, in irregular, slightly dichroic, scales. 

 A little green biotite seems also to occur ; and innumerable, small, greenish yellow crys- 

 tals of rutile are imbedded in the minerals first mentioned. The rutile crystals have 

 sharp relief, frequently form knee-shaped twins, and are almost always associated with 

 grains of a black, opaque mineral that seems to be magnetite.' Rhombohedra of calcite 

 are found scattered through the rock. 



' See plate xviii, fig. 3. 



