22 H. B. PATTON TOURMALIN P: AND TOUIIM ALINE SCHISTS 



of some five or six miles, and then turns westward and climl)s the hills 

 in sharp zigzags until an altitude of 1,000 feet above the base is reached. 

 At the summit the country flattens out and the first mountain ranches 

 begin to appear. On the way U]) the mountain the countr}' rock is well 

 exposed along the road. It consists of micaceous schists of greatly vary- 

 ing degrees of schistosity. Not infrequently they become extremely 

 micaceous and are then beautifully crinkled. The schists are composed 

 of both white and black mica associated with quartz, and sometimes, but 

 not characteristically, with feldspar. One may see at frequent intervals 

 during the ascent numerous veins of quartz or of quartz and feldspar 

 containing the habitual black tourmaline. More extensive exposures, 

 however, occur just before reaching the summit of the long climb op- 

 posite the first piece of cleared land to be seen on the right of the road. 

 There are, in fact, three outcrops, to which attention may be specially 

 directed, differing from each other and from most of the tourmaline oc- 

 currences of this region. They will be described separately. 



First Locality: Tourmaline as a Vein Mineral 



An 18-inch vein of quartz and tourmaline is to be seen striking almost 

 at right angles to the road and exposed in the roadway. The vein is not 

 quite parallel to the cleavage direction of the mica-schists which strike 

 east and west and dip nearly vertically. The tourmaline at this locality 

 is a fine grained schorl-like mass more or less banded wdth wdiite vein 

 quartz. The vein may be traced for two or three hundred feet in the 

 field to the northeast by means of fragments on the surface. Numerous 

 blocks of this rock lie scattered along the road for 50 or 100 feet below 

 the outcrop. 



In most cases tourmaline predominates over quartz. It does not, as 

 is usually the case, occur in coarse grains or crystals, but rather in a dense 

 felted mass, the fibrous character of which is evident only upon a close 

 examination, as the fibers or needles are hardlj'^ over one millimeter in 

 length. The banded structure of the rock is usuall}'' ver}' marked, and 

 the strong contrast between the white of the quartz and the black of the 

 tourmaline is very striking. ^Vhere quartz grains are intimate!}' mixed 

 with tourmaline, as is not infrequently the case, this banding becomes 

 less pronounced or entirely disappears. 



A thin-section of this rock discloses under the microscoj^e granular 

 quartz, sometimes distinct prisms and sometimes irregular grains of tour- 

 maline, together wath a ver}^ little muscovite. In addition to these min- 

 erals may be mentioned a few small, irregular grains that show very 

 high refractive powers and may well be considered rutile. The tour- 

 maline is ver}^ strongly characterized under the microscope. It shows 



