[[Image:Bismuth_hopper_crystal.jpg|thumb|250px|A hopper crystal of metallic bismuth]]
A '''Hopper [[crystal]]''' is one with faces that are [[hollow]]ed as in the "stepped" faces of some [[halite]] crystals.
==Sources==
*Pellant, Chris. ''The Complete Book of Rocks and Minerals'', Dorling Kindersley Inc.: New York (1995), ''p. 251''