26 H. B. PATTON — TOURMALINE AND TOURMALINE SCHISTS 



country rock appeared to carry a little tourmaline, together with a large 

 amount of biotite. 



Of course, this quite agrees with what is generally known about the 

 occurrence of tourmaline. Only a few instances are given, as far as the 

 author is aware, where tourmaline occurs as one of the main ingredients 

 in a schistose rock, without any connection with fissures. Such rocks, 

 for instance, are mentioned by Zirkel as occurring in the Erzgebirge of 

 Saxony.* Usually tourmaline is found near the margin of granite masses, 

 or in the rocks adjacent to large masses of granite, and in either case are 

 considered to be contact features of the granite. 



A case in point, which is similar in some respects to the one under 

 discussion, is the occurrence of tourmaline at Auerberg, in Saxony .f At 

 this locality there is a vein of quartz and tourmaline cutting through a 

 mass of mica-andalusite-hornfels near the junction with the granite. 

 The hornfels, itself a slate rock metamorphosed by contact with granite, 

 has been tourmalinized on both sides of the vein, the tourmaline taking 

 the place of biotite and andalusite. 



Many other cases might be quoted where tourmaline occurs in con- 

 nection with fissures at or near the junction with granite. Apparently, 

 however, there is no true granite in this region ; at least there is no large 

 mass of granite capable of producing ordinary granitic contact phenom- 

 ena. The pegmatite veins of these foothills are usually composed of 

 coarse granular aggregates of reddish microcline and quartz, with or 

 without muscovite, and occasionally garnet. They frequently resemble 

 segregation veins in that they shade off into the adjoining schists without 

 any well defined vein wall. One of the veins on Belcher hill broadens out 

 to a considerable width, but is not as large as many of the pegmatite 

 veins of this region. It ma}' be an intrusive dike, but in the opinion of 

 the writer these and other pegmatite veins of the region are not of such 

 origin. Without entering into the discussion of the origin of the peg- 

 matite veins, the following points may be emphasized in conclusion : 



Summary 



The tourmaline on Belcher hill occurs — 



1. In separate crystals in pegmatite veins. 



2. In black schorl-like masses with quartz, filling fissures in the crys- 

 talline schists. 



3. In mica-schists, at the junction of veins of pegmatite or of quartz, 

 in the form of finely disseminated grains and needles replacing biotite 

 and sometimes feldspar and even quartz. 



* Zirkel : Lehibuch der Petrographie, vol. 3, p. 410. Leipsic, 1894. 

 t Zirkel : Lehrbuch der Petrographie, vol. 2, p. 119. 



