650 PROCEEDINGS OF THE AMERICAN ACADEMY. 



walls of corundophyllite and cut massive emery. The cleavage and 

 general physical appearance of the mineral, together with distinct chem- 

 ical tests obtained for cobalt, arsenic, and sulphur, permit no doubt that 

 these specimens represent cobaltite. The material at hand is not suffi- 

 cient in amount for a quantitative analysis. 



It is interesting to note in this connection that the analyses of ser- 

 pentines of the Chester Formation recorded in Emerson's work 8 show 

 in a number of cases the presence of minute amounts of cobalt and 

 nickel ; in view of this evident source of the material for the formation 

 of the cobaltite it seems probable that analysis of the cobaltite would 

 reveal a nickel content. 



Pi/rite. Pyrite is abundant in the chlorite schist containing tourma- 

 line which traverses the emery deposit on North Mountain. The 

 crystals are quite large, somewhat rounded, and deeply striated cubes.- 

 It is also disseminated rather commonly in the amphibolite that en- 

 closes the emery deposit on South Mountain. 



A number of isolated crystals were obtained after removal of calcite 

 from a veinlet in chlorite schist in which were present also magnetite 

 octahedrons, epidote, titanite in rounded crystals, scales of chlorite, and 

 feldspar anhedra. These crystals show dominant cube with subordi- 

 nate faces of e (210), p (111), and n (211). The crystals are deeply 

 pitted and contain magnetite octahedrons embedded in their mass. 



Pyrite is very rare in the immediate vicinity of the emery. In but 

 a single specimen of one of the corundophyllite veins containing crys- 

 tallized magnetite, corundum, diaspore, etc., we found tiny pyrite 

 crystals of cubical habit with narrow faces of e (210). 



Chalcopyrite. The occurrence of this mineral in crystals has been 

 mentioned above in describing cobaltite. These crystals were attacked 

 by the acid used to remove calcite from the veins and were not meas- 

 urable. They appeared to the eye to be steep, much striated sphenoids. 

 The mineral is very sparingly present in the emery deposit. 



Epidote. Epidote is abundant in the wall rocks of the emery bed and 

 is found in many of the secondary veins. The best crystals obtained 

 by us came from a calcite-filled vein in chlorite schist, together with 

 chlorite and specular ilmenite. The slender epidote needles are pale 

 yellow and quite transparent ; the one crystal measured showed the 

 forms c (001), a (100), u (210), m (110), k (012), o (Oil), n (111), 

 and p (113) ; most of the needles, however, show no terminal planes and 

 are deeply striated parallel to their length. 



Tourmaline. Hexagonal prisms of black tourmaline without distinct 



8 Loc. cit., Monograph, 29, 116. 



