Palache and Merwin — Connellite and Chalcophyllite. 537 



Art. LI. — On Connellite and Chalcophyllite from Bisbee, 

 Arizona; by C. Palache and H. E. Merwin. 



The following note is based on a single specimen of connell- 

 ite sent to the Harvard Mineralogical Laboratory for identifi- 

 cation by Mr. "W. B. Gohring. This one piece, all that was 

 found, came from the Calumet and Arizona mine at Bisbee, 

 and was generously placed at our disposal by Mr. Gohring. 



The specimen is a flat fragment about an inch square con- 

 sisting largely of connellite in groups of radiating needles of 

 characteristic dark blue color. On one side it is incrusted with 

 cuprite and dark green melanochalcite. On breaking it apart 

 a small cavity was exposed, in which w T ere a few terminated 

 needles of connellite, several cubical crystals of cuprite, and 

 several dark green flat crystals of chalcophyllite, mistaken at 

 first for spangolite. 



The needles of connellite are deeply striated lengthwise, but 

 could be adjusted accurately on the two-circle goniometer not- 

 withstanding, and gave fair readings for the terminal planes. 

 These seem to be confined to faces of the unit pyramid ; both 

 first and second order prisms are apparently present. The 

 largest crystal measured was about 05 mm in diameter; the 

 average needle was much more slender, however. 



The average of nine values (on two crystals) for the angle 

 0001 /\ 1011 was 53° 50' corresponding to an axial ratio 

 a : o = 1 : 1*185. This value is much nearer to that of Story- 

 Maskelyne, a : c = 1*156 than to the ratio deduced from Fen- 

 field's measurement of the pyramid angle, a : c== 1*339 ; it is 

 probably based on better measurements than either. 



The needles of connellite show no cleavage. The specific 

 gravity is 3*396, determined by suspension in barium-mercuric 

 iodide (Merwin). 



Optical properties. — (Merwin). Uniaxial, positive. Refrac- 

 tive indices : a> = 1*724 ; e = 1*746 ; determined under the micro- 

 scope by bringing mixtures of monobromonaphthalene and 

 sulphur dissolved, in methylene iodide to match the indices of 

 refraction as nearly as could be done by observing the Becke 

 effect : the refraction of the liquids was then found by means 

 of the reflectometer. The color is a clear, deep, slightly 

 greenish blue even in microscopic fragments. 



The birefringence was determined independently of the 

 refractive indices by the following method : Various-sized 

 minute prisms of the mineral placed between crossed nicols 

 under the microscope showed only three distinct colors, blue, 

 purple and green. In case blue appeared the interference 

 color was, of course, blue, and in case purple appeared the 



