46 F. R. Tan Horn — Pisanite and Arsenojyyrite. 



urination. One crystal measured 5xT mm , and the other was 

 9Xl4 mm . The general habit of both resembled that of danaite 

 or glaucodot rather than that of most arsenopyrite. Blowpipe 

 tests revealed the presence of iron, arsenic and sulphur with 

 just a trace of cobalt, so that the mineral is undoubtedly 

 arsenopyrite rather than danaite. The specific gravity is 6*05. 

 Mr. Walter F. Hunt, Instructor in Mineralogy at the Uni- 

 versity of Michigan, very kindly offered to measure and draw 



the crystals, and I wish to 

 Fig. 6. thank him for his assistance. 



The following forms were 



determined m (110), g'(Oll), 



n (012). 



Angles measured. 



m : ml 68° 39' 



q : q 100° 1' 



n : ri 61° 42' 



The drawing is shown in 



fig. 6 where it is readily seen 



that the largest face is the 



FiG.'e. Arsenopyrite from London brachydome y (Oil) and that 



mine, Ducktown, Tennessee. Drawn the brachydome ft, (012) IS 



by Mr. w. F. Hunt. very small. The habit is 



rather unusual for arseno- 

 pyrite, and as far as the writer can learn, that mineral has also 

 never been previously reported from the Ducktown region. 



Staurolite. 



This mineral has long been known from the general district 

 of eastern Tennessee, western North Carolina, and northern 

 Georgia. Emmons and Laney* have carefully traced certain 

 staurolite layers in the schists of the Ducktown region on 

 account of their probable relation to former sedimentary rocks 

 which had presumably been replaced, with the consequent 

 formation of the iron and copper sulphide deposits. It is the 

 present purpose of the writer only to call attention to a fact of 

 mineralogical interest which has apparently been overlooked, 

 namely the extremely large size of some of the staurolite crys- 

 tals. The largest were found in Mill Creek Valley not far 

 from the Copperhill smelter of the Tennessee Copper Com- 

 pany. The locality was visited three times, each with a dif- 

 ferent section of students, and the writer is not sure but that 

 the students may have collected larger crystals than are shown 

 in fig. 7 which are approximately half the size of the natural 



*Op. cit., p. 158. 



