01 December 2000
Vol 290, Issue 5497

About The Cover

Cover image expansion

COVER Biofilms of sulfate-reducing bacteria (blue) growing in dilute groundwater (~1 part per million dissolved zinc) associated with an abandoned lead-zinc deposit produce sphalerite (ZnS) particles that aggregate (light green) and form micrometer-diameter spheres (gold). Such biomineralization may assist in groundwater remediation and may play a role in the genesis of some ore deposits. See page 1744. [Scanning electron microscope image: J. F. Banfield, S. A. Welch, M. Diman, M. Labrenz]