All, We got a question from chemists looking for crystals like those formed by eulytine with apparent tristetrahedral form. I assume minerals like sphalerite or tetrahedrite might exhibit such forms, but I do not recall seeing any. Surely someone out there knows. George George E. Harlow gharlow@amnh.org<mailto:gharlow@amnh.org> Dept. Earth and Planetary Sciences American Museum of Natural History 200 Central Park West, New York, NY 10024-5102 U.S.A. Phone (212)769-5378 FAX (212)769-5533 WWW: http://www.amnh.org/our-research/staff-directory/george-e.-harlow http://research.amnh.org/eps/jade/