BULL. GEOL. SOC. AM. 



V 







'■^•- f-*r' , ,^ ■ 



VOL. 12, 1900, PL. 33 



Figure 1. — Rigaud Mountain, western Part of the northern Ridge 



Figure 2. — Microphotograph of Rigaud Hornblende-Syenite 



Dark constituent is hornblende intergrown with feldspar in a graphic manner 

 Zonal alteration of hornblende also seen. Ordinary light X 44 



RIGAUD MOUNTAIN AND HORNBLENDE-SYENITE 



