Groups of sharp marcasite crystals, very brilliant, showing the classic forms of "cockscomb". Very stable, defined and partially covering a matrix of small crystals of sphalerite. This matrix presents the known "schalenblende". It is formed by compact sphalerite and wurtzite masses of a pale brown colour, occurring in concentric layers with reniform surfaces which also may contain pyrite and galena. It is believed to have formed by crystallization of a rich-sulfide colloidal dispersion. Good size and aesthetic specimen. 5y3663