Palache — Notes on Tellurides from Colorado. 427 



tufts of wire gold. Two of the steel-gray hessite crystals and 

 a small irregular fragment were detached, the latter yielding 

 before the blowpipe the characteristic reactions of hessite. 



The two crj'stals (figs. 5, 6) which are shown in about their 

 natural proportions in the figures, presented two entirely dif- 

 ferent habits, both hexagonal in appearance ; but measurements 

 proved them to be isometric and combinations of the three 

 forms : 



o, (111); d, (101); and n, (211). 



The hexagonal appearance is due to the development about 

 a trigonal axis, an axis, that is, normal to an octahedral face, 

 and in order to bring out the peculiar symmetry of the distor- 

 tion the drawings have, been made with this trigonal axis ver- 

 tical, as though the crystals were truly hexagonal. 



The difference in habit is due to the fact that different faces 

 of the above forms are developed on the two crystals. In the 

 one, six faces of the trapezohedron equally inclined to the 

 trigonal axis give the effect of a scalenohedron whose summit 

 is modified by a rhombohedron composed of three faces of the 

 dodecahedron, while three octahedron faces form a steeper 

 rhombohedron of the same sign. In the other crystal the habit 

 is prismatic ; three only of the six trapezohedron faces paral- 

 lel to the trigonal axis are developed, yielding a trigonal prism 

 whose edges are beveled by the prism of second order, that is by 

 six planes of the dodecahedron ; the termination consists of posi- 

 tive and negative rhombohedrons consisting of dodecahedron 

 and trapezohedron faces respectively, and a single face of the 

 octahedron forming a basal pinacoid. 



The two habits were represented about equally on the other 

 crystals in the cavity as far as could be judged without their 

 removal. It should be said that the faces present were sharp 

 and clear and no trace of the missing faces of any form could 

 be detected. 



Harvard Mineralogical Laboratory, August, 1900. 



