356 Koenig and Hubbard — Powellite from a new Locality. 



very small strains, in combination with purely kinematical 

 considerations. — There can be no doubt that the law here pro- 

 posed would simplify a great number of problems in the 

 dynamics of the ether and of sound, as well as questions aris- 

 ing in engineering and in geology, because of the simple and 

 plastic nature of the logarithmic function. In the present 

 state of knowledge, the premises of the argument can scarcely 

 be denied ; whether the deductions have been logically made 

 must be decided finally by better judges than myself. 



Washington, D. C, July, 1893. 



Aet. XLIX. — On Powellite from a new Locality ; by 

 George A. Koenig and Lucius L. Hubbard, Michigan 

 Mining School, Houghton. 



The material for this investigation was found in the 21st 

 level of No. 8 shaft South Hecla Copper Mine, Houghton Co., 

 Michigan, in the fall of 1892. It came into the possession of 

 the authors through Mr. John T. Reader of the Tamarack 

 mine*. 



Three small pieces were obtained, which had evidently re- 

 sulted from the breaking up of a larger piece — altogether 

 about 45 grams. In its present condition it appears homo- 

 geneous, that is to say, there is no other mineral associated 

 with it except a trace of native copper. The finder states 

 that the three pieces were lying in a cavity. The specimen, 

 when examined with the lens, exhibits an irregular polysyn- 

 thetic structure. Some of the aggregates terminate in a more 

 or less distinct pyramid. Three of the small groups were 

 detached for measurement. The signals were not very dis- 

 tinct, and the results, therefore, are only approximate. 

 Basal edge 49° 15'; pole edge 19° 59'. 



The powder yields microscopic, positive and uniaxial images 

 and the tetragonal symmetry may be assumed as fairly estab- 

 lished. Mellville* gives for powellite : 



111 a 111 = 49° 12; 111 A 101 = 80° 1'. 



Two cleavages were observed, one distinct and apparently 

 parallel to 111, the other imperfect, parallel to 001. Hardness 

 = 4*5. Spec. Gr. = 4'o49. The color is pale bluish green ; in 

 patches it is deep olive- or asparagus-green. The luster is 

 vitreous and unctuous. A thin section of the mineral under 

 the microscope showed high double refraction (colors of the 



*This Journal, No. 242, p. 138, Febr., 1891. 



