56*0 Professor Emerson on HalFs Geological Collections. 



37. Gneiss. 



A ftray gTanitoid biotite j»;neiss. 

 Xoitli .side of Fiobislier Bay. 



38. Gneiss, 



A lar;ic water-woin bowlder of tiesh-colored biotite-gueiss of even medium 

 jLiiaiii, and quite midecomposed. 



39. Gneiss. 



A large fresh piece of typical gueiss, flesh-colored orthoclase, and more 

 sparingly gray plagioclase, fresh black biotite, and limpid quartz. A single 

 crystal of wine-yellow titanite. 



Frobisher Bay. 



40. Gneiss. 



A much decomposed biotite-gueiss. 

 French Head, Field Bay. 



41. Magnetite gneiss. 



A large unweathered specimen of typical granitoid gneiss, agreeing exactly 

 with the second quality of the rock quarried at Westerly, E. I.; flesh-colored 

 orthoclase, sparingly gray plagioclase, fresh black biotite, very sparingly rauscovite 

 and magnetite, and extremely minute crystals of pyrite. 



Frobisher Bay. 



42. Magnetite gneiss. 



Same as 41, except that the foliation is expressed more by the arrangement 

 of the flesh -colored orthoclase in bauds and less by the position of the biotite. 

 Frobisher Bay. 



43. Magnetite gisteiss. 



A rock of medium grain, consisting of rounded jiortions of orthoclase, quartz, 

 and magnetite of about equal size and quantity, without trace of mica or any 

 accessory. The rock is granitoid in texture, yet distinctly foliated, owing to the 

 position of the different feldspar crystals ; tinged with rust. 



Locality, French Head, Field Bay. 



44. .Ma(jnetite gneiss. 



A large freshly-broken specimen of gray gueiss. In a reddish-white mix- 

 ture of quartz and feldsi^ar are scattered biotite and magnetite in imperfect dodec- 

 ahedrons, with striated faces 5-2 mm. diameter. The magnetite is much more 

 abundant than the biotite, and both are arranged i)aralh'l to the foliation planes. 

 A \'ein ol' segregation runs through the specimens, consisting of flesh-colored 



